Apparatus and method for forging premium coupling blanks

ABSTRACT

A method and apparatus for forging a tubular forging stock to produce a forged product, preferably a premium coupling machining blank. The apparatus includes a holding die assembly defining a holding cavity for the forging stock and a press die apparatus including opposed first and second press dies movable within the holding cavity to forge the forging stock to produce the forged product. The holding die assembly may include opposed first and second holding dies defining respective portions of the holding cavity, wherein the holding dies are selectively relatively movable between a closed position for forging the forging stock and an open position for removal of the forged product. Alternately, the apparatus may include a knockout mechanism for dislodging the forged product from the holding cavity. Further, the apparatus may include a mechanism for controlling finning between the first and second press dies while the forged product is being produced.

TECHNICAL FIELD

The present invention is directed at a forging apparatus and a forgingmethod for producing a forged product from a forging stock. Preferably,the forging stock is a standard American Petroleum Institute (“API”)coupling blank and the forged product is a premium coupling machiningblank.

BACKGROUND OF THE INVENTION

There is a growing demand in the oil and gas industry for Oil CountryTubular Goods (“OCTG”) premium couplings to couple adjacent casing ortubing joints or sections. A typical “premium coupling” includes acentral pin seal and opposed threaded end portions. A compatiblethreaded pin end of the tubing or casing joint is threaded with orscrewed into each respective threaded end portion of the premiumcoupling to abut against the central pin seal. The abutment of the pinend of each tubing or casing joint with the pin seal creates arelatively strong seal upon the application of a sufficient amount oftorque.

The threaded connection of the adjacent casing or tubing joints by meansof the premium coupling may be referred to as a “premium joint.” Thispremium joint tends to have improved sealing properties as compared withstandard OCTG API tubing and casing joints. Further, the premium jointhas been found to permit a relatively large degree of bending ortwisting without causing any significant leaks or mechanical defects.For this reason, premium joints are relatively widely used inspecialized drilling such as Steam Assisted Gravity Drainage (“SAGD”) inthe oil sands, sour gas drilling, offshore drilling or directionaldrilling.

OCTG API “standard couplings” are typically made from steel or stainlesssteel pipe or tubular material referred to as standard API couplingstock. Standard API coupling stock comes in a variety of sizes andgrades. Therefore, the standard API coupling stock is selected toprovide a wall thickness just sufficient to permit the machining of thestandard coupling therefrom. More particularly, a pipe or tubularmaterial having a desired size and grade is selected and cut into anumber of pieces or sections referred to as “cutoffs” or “blanks.” Theblanks are then subjected to machining to produce the desired standardcoupling. The machining process typically includes machining of theouter surface of the blank to provide a consistent outer shape ordimension. Further, the machining process includes “threading” of theinner surface of the blank to permit the threaded connections betweenthe casing or tubing joints. It has been found that about 30% of thematerial comprising the standard coupling blank is typically removedfrom the inner surface during the machining process.

A similar process is applied for the production of premium couplings.However, standard API coupling stock and blanks do not provide asufficient wall thickness to permit the machining of a premium couplingtherefrom. Therefore, the premium coupling is typically made from aheavier or thicker walled “premium coupling stock.” Specifically, thepremium coupling stock must have a greater wall thickness, as comparedwith standard coupling stock, which is sufficient to accommodate orpermit the machining of the central pin seal of the premium coupling. Inother words, the wall thickness of the premium coupling stock must begreater than or equal to the final maximum wall thickness of the premiumcoupling.

Thc need to utilize premium coupling stock increases the overall cost ofproduction of the premium coupling. In addition, the varying wallthickness of the premium coupling along its length, particularly therequirement for the central pin seal, presents further challenges formanufacturing the premium coupling efficiently. In particular, thepremium coupling stock, having the necessary wall thickness toaccommodate the central pin seal, is first “rough bored” to provide apremium coupling blank. The inner surface of the premium coupling blankis then machined to provide the desired configuration of the innersurface of the premium coupling, including the threaded ends and pinseal.

As a result, this process for the production of premium couplingsinvolves a large amount of machining, which increases the productioncosts and tends to result in a relatively large amount of wastedmaterial. For example, it has been found that about 50% of the premiumcoupling stock material may be removed during the process of machiningthe premium coupling from the premium coupling stock. Further, theincreased machining time tends to wear the tools faster, which increasesthe risk of machine down time and increases the tooling expense. As aresult of all of the material inefficiencies, machining inefficienciesand inventory cost inefficiencies arising from the machining of premiumcouplings, such premium couplings tends to be relatively expensive.However, as indicated, the use of premium couplings is often required bythe nature of the drilling or production operation.

In order to reduce some of the disadvantages associated with themachining of the premium coupling blank from premium coupling stock, ithas been found that a premium coupling blank may be forged.Specifically, forging of the premium coupling blank may eliminate orreduce the need for “rough boring” of the premium coupling stock toproduce the premium coupling blank, which may result in a relativelysignificant decrease in material losses.

For example, U.S. Pat. No. 5,363,545 issued Nov. 15, 1994 to Hirano et.al. is directed at a method for producing an OCTG coupling having ametal seal and a screw thread tapered toward its ends. The methodincludes cutting a plain pipe to a predetermined length and hot forgingthe pipe to deform the inside surface to achieve a predeterminedthickened shape. After quenching and tempering the forged piece, theoutside surface is machined into a final dimension. Further, the insidesurface is also machined to a final predetermined shape and threaded toproduce the coupling.

The forging process of Hirano et. al. is performed in a forging machinehaving a one piece outer die with an inside diameter slightly greaterthan the outside diameter of the desired coupling, and therefore, theoutside diameter of the coupling stock to be inserted in the outer die.Further, the forging machine includes an inner die fixed to the insidesurface of the outer die at a closed end of the outer die. Additionally,a punch is insertable within the outer die at the opposed open end ofthe outer die. The plain pipe is heated and inserted into the forgingmachine. Longitudinal compression is applied to the pipe by movement ofthe punch towards the fixed inner die within the outer die. The wallthickness of the plain pipe is about 50%-70% of the maximum wallthickness of the resulting coupling. The length of the plain pipe isabout 110%-140% of the length of the resulting coupling.

Other forging apparatuses or machines are described in United States ofAmerica Publication No. US2004/0139781 A1 published Jul. 22, 2004 byRozhdestvenskiv et. al., United States of America Publication No.US2006/0185417 A1 published Aug. 24, 2006 by Rozhdestvenskiy et. al. andUnited States of America Publication No. US2006/0225480 A1 publishedOct. 12, 2006 by Ishida.

However, neither the forging process and machine of Hirano et. al., norother known forging processes or apparatuses, have been found to befully satisfactory.

Therefore, there remains a need in the industry for an improved forgingapparatus and forging method for producing a forged product from aforging stock. More particularly, there is a need for an improvedforging apparatus and an improved forging method for producing a premiumcoupling blank.

SUMMARY OF THE INVENTION

The present invention is directed at a forging apparatus and a forgingmethod for producing a forged product. Further, the apparatus and themethod are preferably directed at hot forging of the forging stock.

Further, the forged product is preferably a premium coupling machiningblank, also referred to as a “premium coupling blank.” Moreparticularly, the forged product is preferably an Oil Country TubularGoods (“OCTG”) premium coupling blank, which is suitable for thesubsequent production of an OCTG premium coupling therefrom, asdescribed herein.

In order to provide a premium coupling blank having desired materialspecifications or characteristics, or having a desired API Grade,further processing of the forged product is typically required. Forinstance, the premium coupling blank preferably undergoes subsequentheat treating in order to achieve the desired or required materialspecifications of the premium coupling blank. By heat treating theforged premium coupling blank, the material properties of the premiumcoupling blank may be altered to provide a set of material propertieswhich are suitable for later use as a premium coupling.

The forged product is produced or forged from a forging stock. Theforging stock may be a length of any tubular pipe or tubular membercomprised of a material suitable for, and compatible with, forging andsubsequent heat treatment and capable of producing a premium couplingblank having the desired specifications or characteristics, such as adesired API Grade. Further, the forging stock is preferably comprised ofsteel, stainless steel or other suitable metal. Accordingly, the forgingstock may be comprised of standard tubing, tubing blanks, casing orcasing blanks. However, preferably, the forging stock is comprised of alength of standard API coupling stock or a standard API coupling blankor cut-off, comprised of steel or stainless steel pipe. In other words,standard coupling stock is preferably utilized, rather than premiumcoupling stock, in the production of the premium coupling blank.

Thus, preferably, the forging apparatus is configured to produce thepremium coupling machining blank from a length of a tubular pipe as aforging stock, wherein the tubular pipe has a wall thickness, whereinthe premium coupling machining blank has a maximum wall thickness, andwherein the wall thickness of the tubular pipe is less than the maximumwall thickness of the premium coupling machining blank.

In the preferred embodiment, the tubular pipe is comprised of a lengthof standard API coupling stock or a standard API coupling blank orcut-off. Standard API coupling stock typically has a substantiallyuniform wall thickness along the length thereof. Further, the maximumwall thickness of the premium coupling machining blank is preferablydefined by a central pin seal portion, which subsequently provides thepin seal of the premium coupling.

In addition, the premium coupling machining blank has a minimum wallthickness and wherein the wall thickness of the tubular pipe ispreferably greater than the minimum wall thickness of the premiumcoupling machining blank. However, in some embodiments, the wallthickness of the tubular pipe may be less than the minimum wallthickness of the premium coupling blank.

Further, the premium coupling machining blank has a length and whereinthe length of the premium coupling machining blank is preferably greaterthan the length of the tubular pipe. Finally, the outer diameter ordimension of the tubular pipe is preferably about or substantiallysimilar to the outer diameter or dimension of the premium couplingmachining blank.

Thus, in the preferred embodiment, forging of the tubular pipe resultsin a shifting of an amount of the pipe material towards the centre ofthe premium coupling blank to produce a relatively thicker walledportion to accommodate the central pin seal portion of the premiumcoupling blank. Further, forging of the tubular pipe also preferablyresults in an extrusion of the pipe material towards the ends of thepremium coupling blank to provide a longer premium coupling blank ascompared with the tubular pipe.

As stated, in one aspect of the invention, the invention is directed ata forging apparatus. The forging apparatus is preferably comprised of aholding die assembly having a first end and a second end and defining aholding cavity extending between the first end and the second end. Inaddition, the forging apparatus is preferably comprised of a press dieapparatus. The press die apparatus is comprised of a first press die anda second press die, which are preferably movable within the holdingcavity to act upon the forging stock to produce the forged product.

The holding die assembly may be comprised of one or a plurality ofpieces, sections or die components. However, the forging apparatuspreferably permits the forged product to be removed from the forgingapparatus in a relatively easy or efficient manner. Thus, in someembodiments, the forging apparatus is further comprised of a “knockout”mechanism for dislodging the forged product from the forging apparatus,and particularly from the holding die assembly, following the forgingoperation. In particular, a knockout mechanism is preferable where theholding die assembly is comprised of a single outer section or diecomponent. In this instance, the knockout mechanism permits thedislodging of the forged product from the holding cavity following theforging operation.

In further embodiments of the forging apparatus, the holding dieassembly is comprised of a “split” outer die. In other words, at leasttwo outer sections or die components together comprise the holding dieassembly, wherein the die components are relatively movable between aclosed position for forging of the forged product and an open positionto permit removal of the forged product therefrom.

In one such embodiment of the forging apparatus, the forging apparatusis comprised of:

-   -   (a) a holding die assembly having a first end and a second end        and defining a holding cavity extending between the first end        and the second end, the holding die assembly comprising a first        holding die defining a first portion of the holding cavity and        further comprising a second holding die opposed to the first        holding die and defining a second portion of the holding cavity,        wherein the first holding die and the second holding die are        selectively relatively movable toward each other to a closed        position of the holding die assembly and away from each other to        an open position of the holding die assembly, and wherein the        first holding die, the second holding die and the holding cavity        are configured so that a forged product produced by the forging        apparatus may be removed from the holding cavity when the        holding die assembly is in the open position; and    -   (b) a press die apparatus comprising:        -   (i) a first press die which is selectively reciprocable in            order to extend within and withdraw from the holding cavity            from the first end of the holding die assembly; and        -   (ii) a second press die which is selectively reciprocable in            order to extend within and withdraw from the holding cavity            from the second end of the holding die assembly.

In still further embodiments of the forging apparatus, the forgingapparatus may include a finning control mechanism for controllingfinning between the first press die and the second press die while theforged product is being produced by the forging apparatus. In one suchembodiment, the forging apparatus is comprised of:

-   -   (a) a holding die assembly having a first end and a second end        and defining a holding cavity extending between the first end        and the second end;    -   (b) a press die apparatus comprising a first press die and a        second press die opposed to the first press die, wherein the        first press die and the second press die are selectively        relatively movable toward each other within the holding cavity        to a closed position of the press die apparatus and away from        each other to an open position of the press die apparatus;, and    -   (c) a finning control mechanism for controlling finning between        the first press die and the second press die while the forged        product is being produced by the forging apparatus.

As indicated, in some embodiments, the holding die assembly is comprisedof a first holding die and a second holding die opposed to the firstholding die. In this instance, preferably, the first holding die definesa first portion of the holding cavity and the second holding die definesa second portion of the holding cavity. In addition, in suchembodiments, the first holding die and the second holding die define aholding die interface plane. The holding die interface plane preferablyextends between the first end and the second end of the holding dieassembly.

The holding die assembly, including the first holding die and the secondholding die, may be configured such that the holding die interface planehas any orientation compatible with and suitable for the operation ofthe forging apparatus. For instance, the holding die interface plane maybe oriented substantially vertically or horizontally. Preferably, thefirst holding die and the second holding die are configured so that theholding die interface plane is substantially horizontal. In thisinstance, one of the first holding die and the second holding die is abottom holding die, while the other of the first holding die and thesecond holding die is a top holding die.

Further, as indicated, in some embodiments, the first holding die andthe second holding die are selectively relatively movable toward eachother to a closed position of the holding die assembly and away fromeach other to an open position of the holding die assembly. Preferably,one of the first holding die and the second holding die is in a fixedposition and the other of the first holding die and the second holdingdie is movable. Preferably, where the holding die interface issubstantially horizontal, the first holding die is a bottom holding dieand the second holding die is a top holding die, wherein the bottomholding die is fixed and wherein the top holding die is movable.Alternately, the top holding die may be fixed, while the bottom holdingdie is movable. Further, the first holding die, the second holding dieand the holding cavity are configured so that the forged productproduced by the forging apparatus may be removed from the holdingcavity, preferably readily or relatively easily or efficiently, when theholding die assembly is in the open position.

As well, in some of the embodiments of the forging apparatus comprisinga first holding die and a second holding die, the holding die assemblymay be further comprised of a first end retainer which projects into theholding cavity adjacent to the first end of the holding die assembly andwherein the holding die assembly is further comprised of a second endretainer which projects into the holding cavity adjacent to the secondend of the holding die assembly.

The first end retainer and the second end retainer act to retain theforged product in the holding cavity during the release of the press dieapparatus, particularly during the withdrawal of one or both of thefirst press die and the second press die from the holding cavity. Inother words, the first and second end retainers prevent or inhibit theforged product from being pulled along by the first and second pressdies respectively during the withdrawal thereof, thus facilitating thesubsequent removal of the forged product from the forging apparatus.

Preferably, each of the first end retainer and the second end retaineris comprised of one or more retainer members. Further, each of the firstend retainer and the second end retainer is preferably associated withone or both of the first holding die and the second holding die.

In some embodiments, the first holding die may be comprised of aretainer member adjacent to the first end of the holding die assemblyand wherein the first end retainer is comprised of the retainer member.Further, the second holding die may be comprised of a retainer memberadjacent to the first end of the holding die assembly and wherein thefirst end retainer is comprised of the retainer member. However,preferably, the first holding die is comprised of a retainer memberadjacent to the first end of the holding die assembly, the secondholding die is comprised of a retainer member adjacent to the first endof the holding die assembly and wherein the first end retainer iscomprised of the retainer members.

In other embodiments, the first holding die may be comprised of aretainer member adjacent to the second end of the holding die assemblyand wherein the second end retainer is comprised of the retainer member.Further, the second holding die may be comprised of a retainer memberadjacent to the second end of the holding die assembly and wherein thesecond end retainer is comprised of the retainer member. However,preferably, the first holding die is comprised of a retainer memberadjacent to the second end of the holding die assembly, the secondholding die is comprised of a retainer member adjacent to the second endof the holding die assembly and wherein the second end retainer iscomprised of the retainer members.

In the preferred embodiment, the first holding die is comprised of aretainer member adjacent to each of the first end and the second end ofthe holding die assembly, wherein the second holding die is comprised ofa retainer member adjacent to each of the first end and the second endof the holding die assembly, and wherein the first end retainer and thesecond end retainer are comprised of the retainer members.

However, in some embodiments, one or both of the first and secondholding dies may lack the retainer member adjacent one or both of thefirst and second ends of the holding die assembly, particularly ininstances where the presence of the retainer member may impede orinterfere with the removal of the forged product.

Further, as indicated, the forging apparatus is comprised of a press dieapparatus for forging the forging stock held within the holding dieassembly to produce the forged product. The press die apparatus ispreferably adapted to be movable within the holding cavity of theholding die assembly and is configured to provide the forged producthaving a desired shape and configuration.

The press die apparatus is comprised of a first press die and a secondpress die. Preferably, the first press die and the second press die areopposed. Further, the first press die and the second press die arepreferably selectively relatively movable toward each other within theholding cavity to a closed position of the press die apparatus and awayfrom each other to an open position of the press die apparatus. Eitheror both of the first and second press dies may be movable relative tothe other. Preferably, both the first and second press dies areselectively reciprocable. More preferably, the first press die isselectively reciprocable in order to extend within and withdraw from theholding cavity from the first end of the holding die assembly and thesecond press die is selectively reciprocable in order to extend withinand withdraw from the holding cavity from the second end of the holdingdie assembly.

Thus, the first press die and the second press die define a variablepress die gap between them as they relatively move toward and away fromeach other, or as they extend within and withdraw from the holdingcavity. As indicated, the forging apparatus may be further comprised ofthe finning control mechanism for controlling finning between the firstpress die and the second press die. The finning control mechanism ispreferably comprised of a variable spanning device for spanning thepress die gap throughout a range of the press die gap.

The variable spanning device may be comprised of any structure ormechanism capable of spanning, or in other words extending across, thevariable press die gap between the first and second press dies. Forinstance, one or both of the first press die and the second press diemay include an inner member or inner die telescopically received withinthe respective press die such that the inner die is capable of relativereciprocable movement in order to extend or retract therefrom.

Specifically, in some embodiments, the spanning device is comprised ofan inner die telescopically received within a one of the first press dieand the second press die such that the inner die is capable ofreciprocable movement, relative to the one of the first press die andthe second press die, between an extended position and a retractedposition in order to span the press die gap throughout the range of thepress die gap.

However, preferably, the spanning device is comprised of a first innerdie telescopically received within the first press die, wherein thefirst inner die is capable of reciprocable movement relative to thefirst press die between an extended position and a retracted position,and the spanning device is further comprised of a second inner dietelescopically received within the second press die, wherein the secondinner die is capable of reciprocable movement relative to the secondpress die between an extended position and a retracted position.

In addition, the first inner die and the second inner die are adapted toengage each other, preferably within the range of the press die gap, sothat finning between the first press die and the second press die iscontrolled. Thus, the first inner die and the second inner die areadapted to engage each other as at least one, and preferably both, ofthe first press die and the second press die are extended within theholding cavity in order to span the press die gap throughout the rangeof the press die gap.

In one embodiment of the finning control mechanism, the inner die ispreferably biased toward the extended position and movable toward theretracted position by overcoming the bias. Thus, in some embodiments, atleast one of the first inner die and the second inner die is biasedtoward the extended position and movable toward the retracted positionby overcoming the bias. Preferably, the first inner die and the secondinner die are each biased toward the extended position and movabletoward the retracted position by overcoming the bias.

One or both of the first and second inner dies may be biased by anymechanism, structure or orientation capable of providing a biasing forcesufficient to urge the respective inner die toward the extendedposition, while permitting movement toward the retracted position uponovercoming the biasing force. For instance, the forging apparatus, andpreferably the finning control mechanism, may be comprised of a firstbiasing mechanism, such as a spring, for biasing the first inner dietoward the extended position and may further be comprised of a secondbiasing mechanism, such as a spring, for biasing the second inner dietoward the extended position. In this instance, the spring may alsoabsorb some impact shock during the forging operation.

In a more preferred embodiment of the finning control mechanism, theinner die is actuatable toward the extended position. Thus, preferably,at least one of the first inner die and the second inner die isactuatable toward the extended position. More preferably, the firstinner die and the second inner die are each actuatable toward theextended position.

One or both of the first inner die and the second inner die may beactuated to the extended position by any mechanical, hydraulic orelectrical mechanism, device or structure capable of causing the innerdie to extend or reciprocate outwardly relative to the press die. In oneembodiment, the first inner die and the second inner die are eachhydraulically actuatable toward the extended position. Similarly, theinner die, such as one or both of the first inner die and the secondinner die, may be actuated to the retracted position by any mechanical,hydraulic or electrical mechanism, device or structure capable ofcausing the inner die to retract, withdraw or reciprocate inwardlyrelative to the press die.

In a further aspect of the invention, the invention is directed at aforging method for forging the forging stock into the forged product, asdescribed above. The forging method may be performed utilizing anyforging apparatus capable of carrying out the method and each of thesteps thereof. However, preferably, the forging method is performedutilizing the forging apparatus of the within invention, as describedherein.

In addition, the forging method is preferably utilized for hot forgingthe forging stock. Thus, prior to commencement of the forging method asdescribed herein, the forging stock may be heated to a temperaturesuitable for, and compatible with, the subsequent forging of the forgingstock to produce a forged product of a desirable quality.

In one embodiment of the forging method for forging the forging stockinto the forged product, the forging method comprises:

-   -   (a) providing a holding die assembly having a first end and a        second end and defining a holding cavity extending between the        first end and the second end, the holding die assembly        comprising a first holding die defining a first portion of the        holding cavity and further comprising a second holding die        opposed to the first holding die and defining a second portion        of the holding cavity, wherein the first holding die and the        second holding die are selectively relatively movable toward        each other to a closed position of the holding die assembly and        away from each other to an open position of the holding die        assembly;    -   (b) positioning the forging stock between the first holding die        and the second holding die when the holding die assembly is in        the open position;    -   (c) relatively moving the first holding die and the second        holding die toward each other to the closed position of the        holding die assembly so that the forging stock is positioned in        the holding cavity between the first holding die and the second        holding die;    -   (d) providing a first press die which is selectively        reciprocable in order to extend within and withdraw from the        holding cavity from the first end of the holding die assembly,        and providing a second press die which is selectively        reciprocable in order to extend within and withdraw from the        second end of the holding die assembly;    -   (e) extending the first press die within the holding cavity from        the first end of the holding die assembly and extending the        second press die within the holding cavity from the second end        of the holding die assembly in order to forge the forging stock,        thereby producing the forged product;    -   (f) withdrawing the first press die from the holding cavity from        the first end of the holding die assembly and withdrawing the        second press die from the holding cavity from the second end of        the holding die assembly while maintaining the holding die        assembly in the closed position;    -   (g) relatively moving the first holding die and the second        holding die away from each other to the open position of the        holding die assembly; and    -   (h) removing the forged product from the holding cavity while        the holding die assembly is in the open position.

As well, the forging method may further comprise controlling finningbetween the first press die and the second press die while producing theforged product. In one such embodiment, the forging method for forgingthe forging stock into the forged product comprises:

-   -   (a) providing a holding die assembly having a first end and a        second end and defining a holding cavity extending between the        first end and the second end;    -   (b) positioning the forging stock in the holding cavity;    -   (c) providing a press die apparatus comprising a first press die        and a second press die opposed to the first press die, wherein        the first press die and the second press die are selectively        relatively movable toward each other within the holding cavity        to a closed position of the press die apparatus and away from        each other to an open position of the press die apparatus;    -   (d) relatively moving the first press die and the second press        die to the closed position of the press die apparatus in order        to forge the forging stock, thereby producing the forged        product;    -   (e) controlling finning between the first press die and the        second press die while producing the forged product;    -   (f) relatively moving the first press die and the second press        die to the open position of the press die apparatus; and    -   (g) removing the forged product from the holding cavity.

Thus, the holding die assembly, as described, is provided and theforging stock is positioned in the holding cavity. As indicated, ifnecessary, the forging stock is preferably heated to a desirable hotforging temperature prior to positioning the forging stock in theholding cavity. Positioning of the forging stock may accomplished by anymethod or in any manner. For instance, where the holding die assembly iscomprised of a single or unitary piece or component, the forging stockmay simply be inserted through the first or second end into the holdingcavity.

However, where the holding die assembly is comprised of the firstholding die and the second holding die, movable between the openposition and the closed position, the positioning of the forging stockin the holding cavity is preferably comprised of positioning the forgingstock between the first holding die and the second holding die when theholding die assembly is in the open position.

In addition, in such embodiments, the method preferably includesrelatively moving the first holding die and the second holding dietoward each other to the closed position of the holding die assembly sothat the forging stock is positioned in the holding cavity between thefirst holding die and the second holding die, in order to permit theproduction of the forged product. Further, the method preferablyincludes relatively moving the first holding die and the second holdingdie away from each other to the open position of the holding dieassembly, in order to permit removal of the forged product.

The relative moving steps may be comprised of moving one or both of thefirst holding die and the second holding die relative to the otherbetween the open and closed positions of the holding die assembly.Preferably, relatively moving the first holding die and the secondholding die is comprised of maintaining one of the first holding die andthe second holding die in a fixed position while moving the other of thefirst holding die and the second holding die. For instance, the relativemoving step may be comprised of maintaining the first holding die in afixed position while moving the second holding die.

Further, once the forging stock is positioned in the holding cavity, themethod comprises providing a press die apparatus or providing a firstpress die and a second press die, as described herein with respect tothe apparatus.

In some embodiments, the method comprises relatively moving the firstpress die and the second press die to the closed position of the pressdie apparatus in order to forge the forging stock, thereby producing theforged product. The method also comprises relatively moving the firstpress die and the second press die to the open position of the press dieapparatus. Preferably, relatively moving the first press die and thesecond press die to either the open position or the closed positionincludes concurrently or simultaneously moving both the first press dieand the second press die relative to the other.

In further embodiments, the method comprises extending the first pressdie within the holding cavity from the first end of the holding dieassembly and extending the second press die within the holding cavityfrom the second end of the holding die assembly in order to forge theforging stock, thereby producing the forged product. Preferably,extending the first press die and extending the second press die areconducted or performed concurrently or simultaneously. The method alsocomprises withdrawing the first press die from the holding cavity fromthe first end of the holding die assembly and withdrawing the secondpress die from the holding cavity from the second end of the holding dieassembly, preferably while maintaining the holding die assembly in theclosed position. Preferably, withdrawing the first press die andwithdrawing the second press die are also conducted or performedconcurrently or simultaneously.

As well, the method may further comprise retaining the forged product inthe holding cavity while withdrawing the first press die from theholding cavity and withdrawing the second press die from the holdingcavity. The forged product may be retained in the holding cavity in anymanner and by any mechanism or structure capable of inhibiting themovement of the forged product during the withdrawal of the first andsecond press dies. However, where the holding die assembly is comprisedof the first holding die and the second holding die, as describedpreviously, retaining the forged product in the holding cavity may becomprised of gripping the forged product between the first holding dieand the second holding die. In this instance, the forged product may begripped in any manner capable of holding and inhibiting the movement ofthe forged product relative to the first and second holding dies.

In addition, in other embodiments, retaining the forged product in theholding cavity may be comprised of engaging the forged product with afirst end retainer associated with the first end of the holding dieassembly. Retaining the forged product in the holding cavity mayalternately be comprised of engaging the forged product with a secondend retainer associated with the second end of the holding die assembly.However, retaining the forged product in the holding cavity ispreferably comprised of both engaging the forged product with a firstend retainer associated with the first end of the holding die assemblyand engaging the forged product with a second end retainer associatedwith the second end of the holding die assembly. Where at least oneretainer projects into the holding cavity, the holding die assembly iscomprised of the first holding die and the second holding die in orderto permit the movement of the holding die assembly to the open positionfor removal of the forged product.

As well, as indicated, the method may further comprise controllingfinning between the first press die and the second press die whileproducing the forged product. Finning of the material of the forgingstock tends to occur during forging as the first press die and thesecond press die are moved together or into engagement with each otherto produce the forged product. Thus, in some embodiments, finning ispreferably controlled while relatively moving the first press die andthe second press die to the closed position of the press die apparatusin order to forge the forging stock. In other embodiments, finning iscontrolled while extending the first press die within the holding cavityfrom the first end of the holding die assembly and extending the secondpress die within the holding cavity from the second end of the holdingdie assembly in order to forge the forging stock.

In such embodiments, controlling finning is preferably comprised ofspanning the variable press die gap throughout a range of the press diegap. Spanning the press die gap may be comprised of providing thevariable spanning device, as described previously, for spanning thepress die gap throughout a range of the press die gap. Thus, spanningthe press die gap may be further comprised of engaging the first innerdie and the second inner die with each other in order to span the pressdie gap throughout the range of the press die gap.

In one embodiment, spanning the press die gap is further comprised ofbiasing the inner die toward the extended position and moving the innerdie toward the retracted position by overcoming the bias. Preferably,spanning the press die gap is further comprised of biasing at least oneof the first and second inner dies, and more preferably each of thefirst inner die and the second inner die, toward the extended positionand wherein spanning the pres die gap is further comprised of moving atleast one of the first and second inner dies, and more preferably eachof the first inner die and the second inner die, toward the retractedposition by overcoming the bias.

In a more preferred embodiment, spanning the press die gap is furthercomprised of actuating the inner die toward the extended position. Thus,preferably, at least one of the first inner die and the second inner dieis actuated toward the extended position. More preferably, spanning thepress die gap is further comprised of actuating each of the first innerdie and the second inner die toward the extended position. Moreparticularly, spanning the press die gap is preferably further comprisedof hydraulically actuating each of the first inner die and the secondinner die toward the extended position. Similarly, the method mayinclude actuating the inner die, such as one or both of the first innerdie and the second inner die, toward the retracted position, andpreferably hydraulically actuating both the first and second inner dies.Whether being actuated to the extended or retracted position, the innerdie may be actuated in any manner, such as mechanically, hydraulicallyor electrically. However, preferably, the inner die is actuatedhydraulically.

The method also includes removing the forged product from the holdingcavity. Preferably the forged product is removed from the holding cavityin a relatively easy or efficient manner.

In some embodiments, such as where the holding die assembly is comprisedof a single outer section or die component, removing the forged productmay include dislodging the forged product from the holding cavity. Inthis instance, dislodging the forged product is preferably performedusing the knockout mechanism discussed above.

In other embodiments, such as where the holding die assembly iscomprised of a first holding die and a second holding die, the holdingdie is preferably moved to the open position to permit the removal ofthe forged product. In other words, the method includes removing theforged product from the holding cavity while the holding die assembly isin the open position.

The forged product may then be subjected to further treating in order toachieve desired or required material specifications of the forgedproduct. For instance, where the forged product is a premium couplingblank, heat treating may be required to achieve the desired or requiredmaterial specifications or desired API Grade of the premium couplingblank. For instance, the necessary material specifications may bedetermined, at least in part, by the need to machine the premiumcoupling blank to produce the premium coupling, such as an OCTG premiumcoupling, and by the need to provide an OCTG premium coupling suitablefor its intended use. In other words, by beat treating the forgedpremium coupling blank, the material properties of the premium couplingblank may be altered to provide a set of material properties which aresuitable for premium coupling use.

Heat treating of the forged product may include any suitable heattreating technique or combination of techniques suitable for use in heattreating metal components, particularly steel or stainless steel. Insome embodiments, the heat treating of the forged product is preferablycomprised of quenching and tempering, normalizing or annealing.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 is a cross-sectional view of a premium coupling;

FIG. 2 is a cross-sectional view of a forged product, particularly apremium coupling blank, produced by the forging apparatus and forgingmethod of the invention;

FIG. 3 is a schematic side view of a forging apparatus of the inventionfor production of the premium coupling blank shown in FIG. 2, theforging apparatus including a holding die assembly and a press dieapparatus;

FIG. 4 is a detailed view of the holding die assembly and the press dieassembly of the forging apparatus shown in FIG. 3;

FIG. 5 is a detailed view of an alternate holding die assembly for usein the forging apparatus shown in FIG. 3;

FIG. 6 is a schematic side view of an alternate forging apparatus of theinvention including a holding die assembly, a press die apparatus and aknockout mechanism;

FIGS. 7 a-7 b are cross-sectional views of examples of potential finningof a forging stock in the press die apparatus;

FIGS. 8 a-8 c are a side view of the holding die assembly and analternate press die apparatus of the forging apparatus of FIG. 3,wherein the press die apparatus includes a finning control mechanism andwherein FIGS. 8 a, 8 b and 8 c show the operation of the finning controlmechanism in sequence;

FIG. 9 is a detailed side view of a portion of the finning controlmechanism shown in FIG. 8;

FIG. 10 is a detailed side view of a portion of an alternate finningcontrol mechanism; and

FIG. 11 is a schematic diagram of a process for heat treating a forgedproduct produced by the forging method and forging apparatus of theinvention.

DETAILED DESCRIPTION

The present invention is for use in the production of a forged product(20). Preferably, the forged product (20) is a premium coupling blank asshown in FIG. 2. More preferably, the premium coupling blank (20) is anOCTG premium coupling blank suitable for the subsequent production of apremium coupling (22) therefrom, particularly an OCTG premium coupling,of the type shown in FIG. 1.

Referring to FIG. 2, the premium coupling blank (20) is comprised of awall (24) defining a bore (26) extending therethrough between a firstend (28) and a second end (30) of the premium coupling blank (20). Alength (32) of the premium coupling blank (20) is defined between thefirst end (28) and the second end (30). As well, the premium couplingblank (20) defines a wall thickness between an outer surface (34) of thewall (24) and the bore (26). The wall thickness of the premium couplingblank (20) varies through its length (32), as shown in FIG. 2, toprovide a minimum wall thickness (36) of the premium coupling blank (20)and a maximum wall thickness (38) of the premium coupling blank (20).The maximum wall thickness (38) is preferably substantially centrallylocated between the first and second ends (28, 30) in order to provide acentral pin seal portion (40) of the premium coupling blank (20).

The premium coupling blank (20) of FIG. 2 is provided to permit theproduction of the premium coupling (22) therefrom. In particular,following the forging of the premium coupling blank (20) and anysubsequent heat treating, as discussed further below, the bore (26) ofthe premium coupling blank (20) is preferably machined such that thecentral pin seal portion (40) provides a pin seal (41), which may alsobe referred to as torque shoulder or metal seal, of the premium coupling(22). Further, the premium coupling blank (20) is threaded adjacent thefirst and second ends (28, 30) to provide opposed threaded end portions(42) of the premium coupling (22).

Heat treating of the premium coupling blank (20) prior to the subsequentmachining and threading is preferably performed in order to achieve thedesired or required material specifications and API Grade such that therequired premium coupling (22) may be produced. Specifically, heattreating alters the material properties of the premium coupling blank(20) to provide a set of material properties suitable for use as theintended premium coupling (22).

The premium coupling blank (20), being the forged product, is forgedfrom a forging stock comprised of a length of a tubular pipe (44). Theforging stock or tubular pipe (44) is preferably comprised of steel orstainless steel suitable for, and compatible with, forging andsubsequent heat treating in order to produce the premium coupling blank(20) therefrom having desired specifications or characteristics. In thepreferred embodiment, the tubular pipe (44) is comprised of standard APIcoupling stock or a standard API coupling blank or cut-off. Alternately,the tubular pipe (44) may be comprised of a length of standard tubing ora tubing blank.

As shown in FIG. 8 a, the tubular pipe (44) has a first end (46) and anopposed second end (48) and defines a bore (50) extending therethrough.Further, the tubular pipe (44) has a length (52) defined between thefirst and second ends (46, 48) and has a wall thickness (54). The wallthickness (54) is preferably substantially uniform along the length (52)of the tubular pipe (44), although some minor variation in wallthickness is permissible. For instance, where the tubular pipe (44) iscomprised of a standard API coupling blank or cut-off, the outerdimension of the pipe may be inconsistent, due to being “out-of-round”or having rough edges from saw cuts. In circumstances in which the wallthickness (54) of the tubular pipe (44) varies, the wall thickness (54)is defined by the thickest portion or the maximum cross-sectionaldimension through the length (52) of the tubular pipe (44).

The wall thickness (54) of the tubular pipe (44) is preferably less thanthe maximum wall thickness (38) of the premium coupling blank (20).Further, the wall thickness (54) of the tubular pipe (44) is preferablygreater than the minimum wall thickness (36) of the premium couplingblank. (20). However, in some instances, such as where the tubular pipe(44) is comprised of a length of standard tubing or a tubing blank, thewall thickness (54) of the tubular pipe (44) may be less than theminimum wall thickness (36) of the premium coupling blank. (20).

Finally, the length (32) of the premium coupling blank (20) ispreferably greater than the length (52) of the tubular pipe (44). Inthis regard, the length (52) of the tubular pipe (44) is selected, incombination with the wall thickness (54), such that the tubular pipe(44) provides sufficient material for formation or production of thedesired configuration of the premium coupling blank (20), including thecentral pin seal portion (40).

Accordingly, in a preferred embodiment, the forging of the tubular pipe(44) causes a shifting in the material of the tubular pipe (44). First,an amount of the material is shifted centrally to define the maximumwall thickness (38) of the premium coupling blank (20), having adimension sufficient to accommodate the central pin seal portion (40).Second, an amount of the material is preferably extruded or shiftedtowards the ends (28, 30) of the premium coupling blank (20) to providethe desired length (32) of the premium coupling blank (20) and to definethe minimum wall thickness (36) of the premium coupling blank (20).Thus, the forging preferably causes both a localized increase and alocalized decrease in the wall thickness of the resulting premiumcoupling blank (20) as compared with the tubular pipe (44).

Referring to FIGS. 3-4, a forging apparatus (56) is provided. In thepreferred embodiment, the forging apparatus (56) is utilized to producethe forged product, being the premium coupling blank (20), from theforging stock, being the tubular pipe (44). The forging apparatus (56)is comprised of a holding die assembly (58) and a press die apparatus(60).

The holding die assembly (58) has a first end (62), a second end (64)and a holding cavity (66) defined between the first and second ends (62,64). The holding cavity (66) is provided for holding or gripping thetubular pipe (44) during the forging operation and to maintain orprovide an outer dimension of the premium coupling blank (20). Theholding cavity (66) is configured so that the forged premium couplingblank (20) may be readily removed from the holding cavity (66) followingthe forging operation. Further, the press die apparatus (60) iscomprised of a first press die (68) and a second press die (70), whichare movable relative to each other within the holding cavity (66) inorder to act upon the tubular pipe (44) to produce the premium couplingblank (20).

In a preferred embodiment, the holding die assembly (58) is comprised ofgreater than one component or outer die section in order to permit theholding die assembly (58) to be “split” or moved to an open position tomore readily remove the premium coupling blank (20) forged therein. Asshown in FIGS. 3 and 4, the holding die assembly (58) is preferablycomprised of a first holding die (72) and an opposed second holding die(74). The first and second holding dies (72, 74) are movable between aclosed position for forging of the premium coupling blank (20) and anopen position to permit removal of the premium coupling blank (20). Moreparticularly, each of the first and second holding dies (72, 74) definesa part or portion of the complete or entire holding cavity (66). Thus,the first holding die (72) defines a first portion (76) of the holdingcavity (66) and the second holding die (74) defines a second portion(78) of the holding cavity (66). The first and second holding dies (72,74), including the holding cavity (66), are configured so that thepremium coupling blank (20) may be readily removed when the holding dieassembly (58) is in the open position.

Further, if desired or required, the holding die assembly (58) may becomprised of one or more guide pins (not shown). The guide pins are pinsthat are provided to hold or guide the components or outer die sectionsof the holding die assembly (58), or to facilitate or maintain thepositioning of the first and second holding dies (72, 74) relative toeach other, during the forging operation.

The “split” nature of the holding die assembly (58) also permits theholding die assembly (58) to be sized and configured to produce apremium coupling blank (20) of a desired outer dimension or diameter inorder to minimize any subsequent necessary machining of the outersurface (34) of the forged premium coupling blank (20) to produce thepremium coupling (22). Further, the holding cavity (66) is preferablysized and configured such that the outer dimension or diameter of thetubular pipe (44) is substantially similar or identical to the outerdimension or diameter of the forged premium coupling blank (20).Accordingly, a tubular pipe (44) is selected having an outer dimensionor diameter which matches or is substantially similar to the desiredouter dimension or diameter of the required premium coupling (22). As aresult, any necessary machining of the forged premium coupling blank(20) is reduced or minimized.

Where the holding die assembly (58) is not “split”, but is comprised ofa single component or integral holding die, the internal diameter of theholding cavity (66) must be selected to accommodate a wide variety ofpotential shapes of the tubular pipe (44), such as where the tubularpipe (44) is “out-of-round” or has rough edges. As a result, the outerdimension or diameter of the resulting forged premium coupling blank(20) may be too large, requiring an amount of machining to provide thedesired outer dimension or diameter of the premium coupling (22). Use ofa split holding die assembly (58) permits the holding cavity (66) to besized to produce a premium coupling blank (20) having an outer dimensionor diameter more closely matching the desired outer dimension ordiameter of the premium coupling (22), while still accommodating arelatively wide variety of potential shapes of the tubular pipe (44).

Further, the first and second holding dies (72, 74) define a holding dieinterface plane (80) therebetween which extends between the first andsecond ends (62, 64) of the holding die assembly (58). The holding dieinterface plane (80) may be oriented in any direction compatible withthe configuration and operation of the forging apparatus (56). Forexample, as shown in FIG. 6, the holding die interface plane (80) may beoriented substantially vertically.

However, preferably, as shown in FIG. 3, the holding die interface plane(80) is oriented substantially horizontally. Thus, the first and secondholding dies (72, 74) are configured so that the holding die interfaceplane (80) is substantially horizontal. Accordingly, as shown in FIG. 3,the first holding die (72) provides a bottom or lower holding die whilethe second holding die (74) provides a top or upper holding die, whereinthe holding dies (72, 74) are selectively movable toward each other tothe closed position of the holding die assembly (58) and away from eachother to the open position of the holding die assembly (58).

The first or bottom holding die (72) is preferably fixed or held in afixed position by the forging apparatus (56). The second or top holdingdie (74) is movable or adapted to be moved by the forging apparatus(56). The second holding die (74) may be moved by any suitable mechanismor device capable of mechanically, electrically or hydraulicallyactuating the second holding die (74) to move between the open andclosed positions and capable of applying the necessary force or pressurethrough the second holding die (74), or capable of having the first andsecond holding dies (72, 74) locked or held in the closed position, topermit the forging of the tubular pipe (44) within the holding cavity(66). Preferably, the second holding die (74) is hydraulically actuatedbetween the open and closed positions. Thus, the forging apparatus (56)is preferably comprised of a hydraulic press (82) operatively connectedor associated with the second holding die (74). As shown in FIG. 3, thehydraulic press (82) preferably moves the second holding die (74)vertically towards and away from the first holding die (72).

Referring further to FIG. 3, the press die apparatus (60) is comprisedof the first press die (68) and the second press die (70), which areselectively movable relative to each other. For instance, as shown inFIG. 6, one of the first press die (68) and the second press die (70)may be fixed within the holding cavity (66), while the other is movablewithin the holding cavity (66) in order to act upon the tubular pipe(44) therein.

However, as shown in FIGS. 3 and 4, preferably both of the first andsecond press dies (68, 70) are movable. The first and second press dies(68, 70) are movable or extendable toward each other within the holdingcavity (66) to a closed position and are moveable or retractable awayfrom each other to an open position. Specifically, the first press die(68) is selectively reciprocable in order to extend within and withdrawfrom the holding cavity (66) from the first end (62) of the holding dieassembly (58). The second press die (70) is selectively reciprocable inorder to extend within and withdraw from the holding cavity (66) fromthe second end (64) of the holding die assembly (58).

The first and second press dies (68, 70) are oriented to be compatiblewith the orientation of the holding die assembly (58), and particularlythe holding die interface plane (80), such that the first and secondpress dies (68, 70) may access the holding cavity (66). For example, asshown in FIG. 6, where the holding die interface plane (80) is orientedsubstantially vertically, the first and second press dies (68, 70) arcoriented to move or reciprocate along a substantially vertical plane ordirection.

However, as shown in FIGS. 3 and 4, where the holding die interfaceplane (80) is oriented substantially horizontally, the first and secondpress dies (68, 70) are oriented to move or reciprocate along asubstantially horizontal plane or direction. Each of the first andsecond press dies (68, 70) may be moved by any suitable mechanism ordevice capable of mechanically, electrically or hydraulically actuatingthe first or second press die (68, 70) respectively to reciprocatebetween the open and closed positions of the press die apparatus (60)and capable of applying the necessary force or pressure through thepress die apparatus (60) to permit the forging of the tubular pipe (44)within the holding cavity (66).

Preferably, each of the first and second press dies (68, 70) ishydraulically actuated between the open and closed positions. Thus, theforging apparatus (56) is preferably comprised of a hydraulic press (84)operatively connected or associated with each of the first and secondpress dies (68, 70). For instance, as shown in FIGS. 8 and 9, the firstand second press dies (68, 70) may be bolted or otherwise fastened tothe respective hydraulic press (84). As shown in FIG. 3, a pair ofhydraulic presses (84) preferably move the first and second press dies(68, 70) horizontally towards and away from each other to extend withinand withdraw from the holding cavity (66) respectively. As the first andsecond press dies (68, 70) are extended within the holding cavity (66),the tubular pipe (44) is contacted thereby and forged to produce thepremium coupling blank (20). In a preferred embodiment, each of thehorizontal hydraulic presses (84) is capable of applying a press forceof at least about 75 tons (about 68 tonnes).

Further, each of the horizontal hydraulic presses (84) preferablyapplies a substantially identical press force as the press dies (68, 70)are reciprocated towards and away from each other. As well, the firstand second press dies (68, 70) are preferably moved or reciprocatedsimultaneously or concurrently at a substantially similar speed or rateof movement.

Simultaneous or concurrent movement of the first and second press dies(68, 70) towards each other to extend within the holding cavity (66)with a substantially similar force and at a substantially similar speedproduces the premium coupling blank (20) in a relatively centralposition within the holding cavity (66) between the first and secondends (62, 64) of the holding die assembly (58). Simultaneous orconcurrent movement of the first and second press dies (68, 70) awayfrom each other to withdraw from the holding cavity (66) with asubstantially similar force and at a substantially similar speedfacilitates the release of the premium coupling blank (20) by the pressdies (68, 70) and tends to maintain the premium coupling blank (20) inthe relatively central position within the holding cavity (66).

In some embodiments, the holding die assembly (58) may then be moved tothe open position for removal of the premium coupling blank (20) fromthe forging apparatus (56). Otherwise, the premium coupling blank (20)may need to be dislodged from the holding cavity (66).

In order to reduce wear on the press die apparatus (56), and to enhancethe efficiency of the forging apparatus (56) and method, the tubularpipe (44) is preferably heated prior to forging such that the tubularpipe (44) undergoes hot forging, as compared to cold forging. Hot andrelatively slow forging of the tubular pipe (44) permits the hydraulicpresses (82, 84) to operate at a tonnage as low as about 75 tons. Thus,the forging temperature is selected depending upon various factorsincluding the desire to maximize the quality of the forged product, toreduce wear of the forging apparatus (56) and to enhance the efficiencyof the forging method.

Referring to FIG. 5, in some of the embodiments of the forging apparatus(56) in which the holding die assembly (58) is comprised of the firstand second holding dies (72, 74), the holding die assembly (58) isfurther comprised of a first end retainer (86) and a second end retainer(88). The first and second end retainers (86, 88) act, at least in part,to maintain or assist in maintaining the premium coupling blank (20) inthe holding cavity (66) during the withdrawal of the first and secondpress dies (68, 70) from the holding cavity (66). As a result, the firstand second end retainers (86, 88) facilitate the release of the premiumcoupling blank (20) by the first and second press dies (68, 70).

As shown in FIG. 5, the first end retainer (86) preferably projects intothe holding cavity (66) adjacent to the first end (62) of the holdingdie assembly (58). The second end retainer (88) similarly preferablyprojects into the holding cavity (66) adjacent to the second end (64) ofthe holding die assembly (58). Each of the first end retainer (86) andthe second retainer (88) is associated with both of the first holdingdie (72) and the second holding die (74).

In particular, the first holding die (72) includes a first retainermember (90) adjacent to the first end (62) of the holding die assembly(58). Similarly, the second holding die (74) includes a first retainermember (92) adjacent to the first end (62) of the holding die assembly(58), which is compatible with the first retainer member (90) of thefirst holding die (72). Thus, the first end retainer (86) is comprisedof the first retainer members (90, 92) of the first and second holdingdies (72, 74) respectively.

As well, the first holding die (72) includes a second retainer member(94) adjacent to the second end (64) of the holding die assembly (58).Similarly, the second holding die (74) includes a second retainer member(96) adjacent to the second end (64) of the holding die assembly(58),which is compatible with the second retainer member (94) of the firstholding die (72). Thus, the second end retainer (88) is comprised of thesecond retainer members (94, 96) of the first and second holding dies(72, 74) respectively.

Each of the first retainer members (90, 92) and each of the secondretainer members (94, 96) is comprised of a projection or protrusionextending into the holding cavity (66) and adapted to abut against orotherwise engage the premium coupling blank (20) positioned in theholding cavity (66). The projection may have any dimensions andconfiguration suitable for performing its intended function as describedherein. However, preferably, each of the first end retainer (86) and thesecond end retainer (88) projects into the holding cavity (66) along aset of arcs that, in sum, are substantially about the circumference ofthe holding cavity (66) and that are approximately evenly spaced aboutsuch circumference. Further, preferably, the set of arcs are no deeperthan the minimum wall thickness (36) of the premium coupling blank (20).In a preferred embodiment, each of the first end retainer (86) and thesecond end retainer (88) projects into the holding cavity (66)substantially about the complete circumference or inner dimension of theholding cavity (66).

Accordingly, as the first press die (68) is withdrawn from the holdingcavity (66), the first end (28) of the premium coupling blank (20) abutsagainst and engages the first end retainer (86) and is inhibited frommovement with, or being drawn along by, the first press die (68).Similarly, as the second press die (70) is withdrawn from the holdingcavity (66), the second end (30) of the premium coupling blank (20)abuts against and engages the second end retainer (88) and is inhibitedfrom movement with, or being drawn along by, the second press die (70).Thus, the premium coupling blank (20) is retained in a substantiallycentral position within the holding cavity (66).

The invention is also directed at a forging method for forging theforging stock into the forged product, and is preferably performed orcarried out utilizing the forging apparatus (56). Thus, the forgingmethod comprises providing the holding die assembly (58) and positioningthe tubular pipe (44) in the holding cavity (66). For instance,referring to FIG. 6, the tubular pipe (44) may simply be insertedthrough one of the first or second ends (62, 64) of the holding dieassembly (58) into the holding cavity (66).

However, referring to FIGS. 3 and 4, the tubular pipe (44) is preferablypositioned between the first and second holding dies (72, 74) when theholding die assembly (58) is in the open position. In this embodiment,the method further includes moving the first and second holding dies(72, 74) relatively toward each other to the closed position of theholding die assembly (58) such that the tubular pipe (44) is positionedwithin the holding cavity (66).

Relatively moving the first and second holding dies (72, 74) may beperformed in any manner and by any process capable of achieving theclosed position of the holding die assembly (58). Preferably, the methodincludes maintaining one of the first holding die (72) and the secondholding die (74) in a fixed position while moving the other of the firstholding die (72) and the second holding die (74). Referring to FIGS. 3and 4, in a preferred embodiment, the second holding die (74) is movedin a substantially vertical direction or in a substantially verticalplane towards the fixed first holding die (72) by the vertical hydraulicpress (82). Alternately, the first and second holding dies (72, 74) maybe moved simultaneously or concurrently towards each other to the closedposition.

Further, the method includes providing the press die apparatus (60), andparticularly the first and second press dies (68, 70). Once the tubularpipe (44) is positioned in the holding cavity (66), the first and secondpress dies (68, 70) are moved relatively towards each other, to theclosed position of the press die apparatus (60), in order to forge thetubular pipe (44) to produce the premium coupling blank (20).

Relatively moving the first and second press dies (68, 70) may beperformed in any manner and by any process capable of achieving theclosed position of the press die apparatus (60). For instance, referringto FIG. 6, the method may include maintaining one of the first andsecond press dies (68, 70) in a fixed position while moving the other ofthe first and second press dies (68, 70). However, preferably, referringto FIGS. 3 and 4, the first and second press dies (68, 70) are movedsimultaneously or concurrently to the closed position.

Referring to FIGS. 3 and 4, in a preferred embodiment, the methodcomprises extending the first press die (68) within the holding cavity(66) from the first end (62) of the holding die assembly (58) andextending the second press die (70) within the holding cavity (66) fromthe second end (64) of the holding die assembly (58) in order to forgethe tubular pipe (44) positioned within the holding cavity (66).

Extending the first press die (68) and extending the second press die(70) are conducted or performed concurrently or simultaneously. Moreparticularly, the first and second press dies (68, 70) are concurrentlyor simultaneously moved towards each other, at substantially similarspeeds and applying substantially similar press forces, in asubstantially horizontal direction or along a substantially horizontalaxis by the horizontal hydraulic presses (84). Thus, the pressureexerted on the tubular pipe (44) by the first and second press dies (68,70) is applied equally and evenly such that the deformation of thetubular pipe (44) may be controlled to produce the desired premiumcoupling blank (20).

Once the tubular pipe (44) is forged, the first and second press dies(68, 70) are moved relatively away from each other, to the open positionof the press die apparatus (60). Relatively moving the first and secondpress dies (68, 70) away from each other may be performed in any mannerand by any process capable of achieving the open position of the pressdie apparatus (60). For instance, referring to FIG. 6, the method mayinclude maintaining one of the first and second press dies (68, 70) in afixed position while moving the other of the first and second press dies(68, 70). However, preferably, referring to FIGS. 3 and 4, the first andsecond press dies (68, 70) arc moved simultaneously or concurrently awayfrom each other to the open position.

Referring to FIGS. 3 and 4, in a preferred embodiment, the methodcomprises withdrawing the first press die (68) from the holding cavity(66) from the first end (62) of the holding die assembly (58) andwithdrawing the second press die (70) from the holding cavity (66) fromthe second end (64) of the holding die assembly (58), while maintainingthe holding die assembly (58) in the closed position. Withdrawing thefirst press die (68) and withdrawing the second press die (70) areconducted or performed concurrently or simultaneously. Moreparticularly, the first and second press dies (68, 70) are concurrentlyor simultaneously moved away from each other, at substantially similarspeeds and applying substantially similar withdrawal forces, in asubstantially horizontal direction or along a substantially horizontalaxis by the horizontal hydraulic presses (84).

The forged premium coupling blank (20) is then removed from the holdingcavity (66). If necessary, removing the premium coupling blank (20) mayinclude dislodging the premium coupling blank (20) from the holdingcavity (66). The premium coupling blank (20) may be dislodged, releasedor “loosened” from the holding cavity (66) to facilitate its removalfrom the holding die assembly (58) in any manner or by any method ormechanism. For instance, in some embodiments, a “knockout” mechanism(98), as shown in FIG. 6, may be utilized. The knockout mechanism (98)is of particular use where the holding die assembly (58) is comprised ofa single or unitary component, such that the holding die assembly (58)is not movable to an open position.

In the preferred embodiment, the holding die assembly (58) includes thefirst and second holding dies (72, 74). Accordingly, prior to removingthe premium coupling blank (20), the method includes relatively movingthe first and second holding dies (72, 74) away from each other to theopen position of the holding die assembly (58). The method then includesremoving the premium coupling blank (20) from the holding cavity (66)while the holding die assembly (58) is in the open position.

Relatively moving the first and second holding dies (72, 74) away fromeach other may be performed in any manner and by any process capable ofachieving the open position of the holding die assembly (58).Preferably, the method includes maintaining one of the first and secondholding dies (72, 74) in a fixed position while moving the other of thefirst and second holding dies (72, 74). Referring to FIGS. 3 and 4, in apreferred embodiment, the second holding die (74) is moved in asubstantially vertical direction or in a substantially vertical planeaway from the fixed first holding die (72) by the vertical hydraulicpress (82). Alternately, the first and second holding dies (72, 74) maybe moved simultaneously or concurrently away from each other to the openposition.

Preferably, the premium coupling blank (20) is retained in the holdingcavity (66) during the withdrawal of the first and second press dies(68, 70). If withdrawal of the first and second press dies (68, 70) isconcurrent or simultaneous, this fact alone may suffice to cause thepremium coupling blank (20) to be retained in the holding cavity (66).However, where required, the method may further include activelyretaining the premium coupling blank (20) in the holding cavity (66)while relatively moving the first and second press dies (68, 70) awayfrom each other or while withdrawing one or both of the first and secondpress dies (68, 70) from the holding cavity (66). Retaining the forgedproduct may be performed in any manner or by any method capable ofinhibiting or preventing the movement of the forged product within theholding cavity (66).

For instance, as shown in FIGS. 3 and 4, where the holding die assembly(58) includes the first and second holding dies (72, 74), retaining thepremium coupling blank (20) may be comprised of gripping the premiumcoupling blank (20) between the first and second holding dies (72, 74).A sufficient gripping force may be applied to the premium coupling blank(20) to inhibit or prevent the movement of the premium coupling blank(20) relative to the first and second holding dies (72, 74).

However, retaining the premium coupling blank (20) in the holding cavity(66) is preferably comprised of engaging the premium coupling blank (20)with at least one, and preferably both, of the first end retainer (86)and the second end retainer (88). More particularly, referring to FIG.5, retaining the premium coupling blank (20) in the holding cavity (66)is comprised of engaging the first end (28) of the premium couplingblank (20) with the first end retainer (86), preferably by abutting thefirst retainer members (90, 92) against or with the first end (28) ofthe premium coupling blank (20). In addition, retaining the premiumcoupling blank (20) in the holding cavity (66) is further comprised ofengaging the second end (30) of the premium coupling blank (20) with thesecond end retainer (88), preferably by abutting the second retainermembers (94, 96) against or with the second end (30) of the premiumcoupling blank (20).

The forging apparatus (56) preferably permits the forged product to beremoved from the forging apparatus (56) in a relatively easy orefficient manner. In a preferred embodiment, this is achieved byproviding the holding die assembly (58) with the first and secondholding dies (72, 74) and moving them to the open position. However, insome embodiments, the holding die assembly (58) is comprised of a singlecomponent or unitary holding die which is not movable to an openposition. In such embodiments, a knockout mechanism (98) is preferablyprovided for dislodging the premium coupling blank (20) from the holdingcavity (66) such that the premium coupling blank (20) may be more easilyor readily removed from the holding die assembly (58).

Referring to FIG. 6, the forging apparatus (56) is comprised of aholding die assembly (58) which is not adapted or configured to bemovable to an open position. Further, the press die apparatus (60) iscomprised of the first and second press dies (68, 70), which are movablerelative to each other. During the forging method, the first or bottompress die (68) is fixed or stationary, while the second or top press die(70) moves towards the first press die (68), within the holding cavity(66) to forge the tubular pipe (44) and produce the premium couplingblank (20). Following the forging operation, the second press die (70)is relatively moved away from the first press die (68), resulting in thewithdrawal of the second press die (70) from the holding cavity (66).

Typically, upon withdrawal of the second press die (70) and movement tothe open position of the press die apparatus (60), the premium couplingblank (20) tends to remain within the holding cavity (66). The knockoutmechanism (98) is provided for exerting a force on the premium couplingblank (20) causing the premium coupling blank (20) to move within theholding cavity (66) relative to the holding die assembly (58).Preferably, where the forging apparatus (56) is configured as shown inFIG. 6, an upward, vertically directed force is applied to the premiumcoupling blank (20) such that the premium coupling bank (20) isremovable from the holding cavity (66) from the second or top end (64)of the holding die assembly (58).

FIG. 6 depicts a preferred embodiment of the knockout mechanism (98).The holding die assembly (58) is substantially vertically oriented suchthat the first end (62) is contacted with and supported in the desiredposition on a holding die assembly supporting surface (100) of theforging apparatus (56), which may be referred to as the “work table.”

Further, the knockout mechanism (98) comprises a dislodging or knockoutplate (102) which is inserted within the holding cavity (66), preferablyadjacent the first end (62) of the holding die assembly (58). Thedislodging plate (102) has a first or lower surface (104) and an opposedsecond or upper surface (106).

The second or upper surface (106) of the dislodging plate (102) isconfigured to engage the forged product, preferably the first end (28)of the premium coupling blank (20), when the dislodging plate (102) isinserted in the holding cavity (66). Further, the second or uppersurface (106) of the dislodging plate (102) defines a recess (107)therein which is configured to be compatible with the first or bottompress die (68) such that the first press die (68) may be received withinthe recess (107) of the second surface (106) of the dislodging plate(102), as described further below.

The first or lower surface (104) of the dislodging plate (102) isconfigured to be supportable upon the supporting surface (100). Inaddition, the first surface (104) defines a recess (108) for receiving acompatible lifting or knockout bar (110), as discussed further below.

As shown in FIG. 6, during the forging operation to produce the forgedproduct, the first surface (104) of the dislodging plate (102) issupported upon the supporting surface (100). Further, the first pressdie (68) is preferably supported within the recess (107) a spaceddistance from the second surface (106) of the dislodging plate (102).For this purpose, at least one lift block (112) is preferably providedto support the first press die (68) in the desired position within therecess (107). The lift block (112) is provided, at least in part, toabsorb a portion of the pressure exerted on the first press die (68)during the forging process. Although any type of lift block (112) orother lifting or spacing structure capable of absorbing the desiredforces of the press die apparatus (60) may be used, the lift block (112)preferably passes through the dislodging plate (102) to extend betweenthe supporting surface (100) and the first press die (68) and is of asufficient length to support the first press die (68) the desireddistance from the second surface (106) of the dislodging plate (102). Inthe preferred embodiment, the lift block (112) is fixed to thesupporting surface (100) and the dislodging plate (102) is slidablymovable on the lift block (112) to permit the movement of the dislodgingplate (102) relative to the lift block (112).

As indicated, the knockout mechanism (98) is further comprised of thelifting bar (110). The lifting bar (110) is received within the recess(108) on the first surface (104) of the dislodging plate (102) such thatmovement of the lifting bar (110) in the direction of the dislodgingplate (102) results in a corresponding movement of the dislodging plate(102). Preferably, the movement of the lifting bar (110) towards thedislodging plate (102) is provided in a substantially verticaldirection, resulting in a substantially vertical movement of thedislodging plate (102). The lifting bar (110) may be mechanically,electrically or hydraulically actuated to move in the direction of thedislodging plate (102) by any suitable mechanism or structure capable ofproviding the required or desired lifting force to achieve the purposesdescribed herein. In the preferred embodiment of FIG. 6, the knockoutmechanism (98) includes at least one hydraulic cylinder (114),operatively connected with the lifting bar (110), for hydraulicallyactuating the lifting bar (110) to move.

In operation, following the forging of the forged product, the secondpress die (70) is removed or withdrawn from the holding cavity (66), ina manner as described previously, such as by actuation of the hydraulicpress (84). Subsequently, the hydraulic cylinder (114) actuates thelifting bar (110) to move upwards, or in the direction of the dislodgingplate (102). As a result, the dislodging plate (102) is moved upwardlywithin the holding cavity (66), in a direction away from the first end(62) of the holding die assembly (58) and towards the second end (64).The engagement of the second surface (106) of the dislodging plate (102)with the first end (28) of the premium coupling blank (20) causes thepremium coupling blank (20) to correspondingly move within the holdingcavity (66).

Thus, the movement of the dislodging plate (102) causes the premiumcoupling blank (20) to be dislodged or released from the holding dieassembly (58). However, typically, the first press die (68) moves withthe premium coupling blank (20) as the premium coupling blank (20) ismoved or lifted by the dislodging plate (102). Therefore, once thepremium coupling blank (20) is dislodged from the holding cavity (66),further movement of the dislodging plate (102) ceases. A rod (116) isthen inserted, either manually or preferably automatically, within theholding cavity (66) from the second end (64) of the holding die assembly(58).

More particularly, as shown in FIG. 6, one end of the rod (116) ispreferably abutted against the first press die (68). Subsequently, thepremium coupling blank (20) may be dislodged or released from the firstpress die (68) either by moving the rod (116) and the first press die(68) while maintaining the position of the premium coupling blank (20)or by moving the premium coupling blank (20) while maintaining thepositions of the rod (116) and the first press die (68).

In the first instance, movement of the rod (116) in the direction of thefirst end (62) of the holding die assembly (58) applies a force to thefirst press die (68) which causes a corresponding movement of the firstpress die (68). As a result of the engagement of the premium couplingblank (20) with the dislodging plate (102), movement of the first pressdie (68) towards the first end (62) of the holding die assembly (58)causes the premium coupling blank (20) to be dislodged or released fromthe first press die (68). The first press die (68) is then receivedwithin the recess (107) of the second surface (106) of the dislodgingplate (102) and further movement of the rod (116) ceases.

The force may be applied to the rod (116) to move the rod (116) anddislodge the first press die (68) in any manner and by any mechanism orstructure capable of applying the required force. However, preferably,as shown in FIG. 6, following the abutment of one end of the rod (116)against the first press die (68), the second press die (70) is broughtinto engagement with the other end of the rod (116). Thus, the force maybe applied to the rod (116) through the actuation of the second pressdie (70), such as by the hydraulic press (84).

In the alternative instance, further movement of the dislodging plate(102) in the direction of the second end (64) of the holding dieassembly (58) causes a corresponding movement of the premium couplingblank (20) as a result of the engagement of the premium coupling blank(20) with the dislodging plate (102). The rod (116) prevents or inhibitsa corresponding movement of the first press die (68), resulting in thedislodging or release of the premium coupling blank (20) from the firstpress die (68). Once the first press die (68) is received within therecess (107) of the second surface (106) of the dislodging plate (102),further movement of the dislodging plate (102) ceases.

Once the premium coupling blank (20) is dislodged from both the holdingdie assembly (58) and the first press die (68), the second press die(70) or the dislodging plate (102), as the case may be, is retractedsufficiently to permit the removal of the rod (116), and the rod (116)is removed. The dislodging plate (102) is then further moved in adirection towards the second end (64) of the holding die assembly (58),causing a corresponding movement of the premium coupling blank (20).When the premium coupling blank (20) is lifted sufficiently within theholding cavity (66), the premium coupling blank (20) may be removed formthe forging apparatus (56).

Referring to FIGS. 7-10, in further embodiments of the forging apparatus(56) and forging method, the forging apparatus (56) may include afinning control mechanism (118) and the method may include controlling“finning” or “heading” between the first and second press dies (68, 70)while the forged product is being produced. More particularly, “finning”refers to the seepage of material into the press die gap. Finning isparticularly undesirable if such seepage causes the wall thickness ofthe forged product (20) to exceed the desired maximum wall thickness(38) and/or to fall below a desired outside diameter. The method forcontrolling finning is preferably performed utilizing the finningcontrol mechanism (118) described herein.

Due to the redistribution of the material of the tubular pipe (44)during forging, a potential exists for undesired “finning”, “heading” or“upsetting” to form between the first and second press dies (68, 70) asthey are moved toward each other. Referring to FIG. 7, examples ofpotential undesirable “finning” of the tubular pipe (44) between thefirst and second press dies (68, 70) are shown. The first press die (68)and the second press die (70) define a variable press die gap (120)between them as they relatively move toward and away from each other, oras they extend within and withdraw from the holding cavity (66). Finningof the material of the tubular pipe (44) occurs when a portion of thematerial of the tubular pipe (44) extrudes into the variable press diegap (120) as the first and second press dies (68, 70) move togetherwithin the holding cavity (66). The material extruded within thevariable press die gap (120) forms a “fin” (122), “head” or “upset”,which prevents the first and second press dies (68, 70) from engagingeach other within the holding cavity (66).

Finning is undesirable in the production of the premium coupling blank(20) as it may result in the shortage of material from the tubular pipe(44) to produce a premium coupling blank (20) of the desired shape orconfiguration. Further, subsequent machining of the forged premiumcoupling blank (20) may be impeded or rendered more difficult by thepresence of the fin (122). It has been found that finning is moreprevalent where the tubular pipe (44) is comprised of a standard APIcoupling blank or where the wall thickness and/or the length of thetubular pipe (44) is insufficient. However, finning is less prevalentwhere the tubular pipe (44) is-comprised of a standard tubing blank orwhere the wall thickness and the length of the tubular pipe (44) issufficient In this instance, a finning control mechanism (118) may notbe required.

Referring to FIGS. 8-10, the finning control mechanism (118) ispreferably comprised of a variable spanning device (124) for spanning orextending across the press die gap (120), throughout all or part of therange of the press die gap (120), between the first and second pressdies (68, 70). Specifically, the variable spanning device (124)preferably crosses and “fills” the variable press die gap (120) as thefirst and second press dies (68, 70) are moving toward each other inorder to prevent or inhibit the extrusion of material into the gap(120). For instance, a central portion or center part of each press die(68, 70) preferably extends toward the other when the press dies (68,70) are not fully abutted or are not in the closed position of the pressdie apparatus (60). Upon engagement or abutment of the central portions,the central portions are capable of retraction in order to permit thepress dies (68, 70) to be further moved together to the closed positionof the press die apparatus (60).

The particular structure of the finning control mechanism (118)described herein also permits the forging apparatus (56) to more readilyadjust to or accommodate different or varying lengths of the tubularpipe (44). For instance, the extension of the central portions of eachpress die (68, 70) will permit the press die apparatus (60) toaccommodate a longer length of tubular pipe (44). In this case, anyexcess material of the tubular pipe (44) will tend to be added to thepremium coupling blank (20) at its length.

Preferably, the variable spanning device (124) is comprised of an innerdie telescopically or slidably received within one, and more preferablyboth, of the first press die (68) and the second press die (70). As aresult, the inner die is capable of reciprocable movement relative tothe respective press die (68, 70) in order to extend or retracttherefrom.

In the preferred embodiment of the variable spanning device (124), afirst inner die (126) is telescopically received within the first pressdie (68) and a second inner die (128) is telescopically received withinthe second press die (70). Each of the first and second inner dies (126,128) is capable of reciprocable movement relative to the first andsecond press dies (68, 70) respectively between an extended position anda retracted position. The first and second inner dies (126, 128) areconfigured or adapted to engage or abut each other throughout anappropriate or required range of the variable press die gap (120) inorder to control or limit any potential finning therebetween.Specifically, the first and second inner dies (126, 128) preferablyengage or abut each other to span the press die gap (120) at anappropriate location or point before the first and second press dies(68, 70) reach their extended positions within the holding cavity (66).

Referring to FIGS. 8 and 9, in one embodiment of the finning controlmechanism (118), at least one, and preferably both, of the first innerdie (126) and the second inner die (128) is biased toward the extendedposition. Thus, each of the first and second inner dies (126, 128) ismovable to the retracted position by overcoming the bias. As shown indetail in FIG. 9, each inner die (126, 128) is slidably received withinits respective press die (68, 70). Each inner die (126, 128) has anouter end (130) configured for abutment or engagement with the outer end(130) of the other inner die (126, 128) as described above. The innerdies (126, 128) may comprise guide pins (not shown) to assist thealignment of the inner dies (126, 128) with respect to the holdingcavity (66). Further, each inner die (126, 128) has an opposed inner end(132) configured and adapted for contact with a biasing mechanism forurging the inner die (126, 128) towards its extended position.

As well, the inner end (132) is preferably configured or adapted toinhibit or prevent the movement of the inner die (126, 128) out of thepress die (68, 70). In other words, the inner end (132) provides amechanism for retaining the inner die (126, 128) within the press die(68, 70) when moved to its fully extended position. For instance, theinner end (132) of each of the first and second inner dies (126, 128)may include a shoulder (136) for engaging a compatible shoulder (138)defined by the respective press die (68, 70), as shown in FIG. 9. Anyalternate retaining mechanism may be utilized which is capable ofpreventing or inhibiting the removal of the inner die (126, 128) fromthe press die (68, 70).

Each biasing mechanism provides a biasing force sufficient to urge theinner die (126, 128) toward its extended position, and preferably tomove the inner die (126, 128) to the fully extended position, while alsopermitting movement of the inner die (126, 128) toward the retractedposition. The particular biasing mechanism will be selected based, atleast in part, upon the anticipated press forces to be applied by thepress die apparatus (60). In a preferred embodiment, a first biasingmechanism (134) is provided for biasing the first inner die (126) towardthe extended position and a second biasing mechanism (135) is providedfor biasing the second inner die (128) toward the extended position.Preferably, each of the first and second biasing mechanisms (134, 135)is comprised of a spring extending between the inner end (132) of theinner die (126, 128) and a support block (140) configured to receive andsupport an end of the spring therein. In some embodiments, the pressurewhich is built up during the forging operation inside the biasingmechanism (134, 135) may be sufficient enough to replace the function ofthe springs.

Referring to FIGS. 8( a), 8(b) and 8(c), the forging method, includingthe method for controlling finning, is shown in sequence using thefinning control mechanism (118) of FIG. 9. As shown in FIG. 8( a), inboth the open position of the holding die assembly (58) and the openposition of the press die apparatus (60), the tubular pipe (44) isplaced in the holding cavity (66). Further, the inner die (126, 128) ofeach of the press dies (68, 70) is in the extended position.

Referring to FIG. 8( b), the holding die assembly (58) and the press dieapparatus (60) are moved to their respective closed positions. As thefirst and second press dies (68, 70) are extended within the holdingcavity (66), the first and second inner dies (126, 128) span thevariable press die gap (120) and engage each other. Upon furthermovement of the press die apparatus (60) toward the closed position, thefirst and second inner dies (126, 128) are moved toward their respectiveretracted positions, as shown in FIG. 8( b). Finally, referring to FIG.8( c), following the production of the forged product, the holding dieassembly (58) and the press die apparatus (60) are returned to theirrespective open positions, and the inner die (126, 128) of each of thepress dies (68, 70) is returned to its extended position.

Referring to FIG. 10, in an alternate preferred embodiment of thefinning control mechanism (118), at least one, and preferably both, ofthe first inner die (126) and the second inner die (128) is actuatabletoward the extended position. As described previously, each inner die(126, 128) is slidably received within its respective press die (68,70). Each inner die (126, 128) has an outer end (130) configured forabutment or engagement with the outer end (130) of the other inner die(126, 128) as described above. Further, each inner die (126, 128) has anopposed inner end (132) configured and adapted for engagement with orcontact by an actuator (142) for moving or actuating the inner die (126,128) towards its extended position.

The actuator (142) may be comprised of any mechanical, hydraulic orelectrical mechanism, device or structure capable of actuating therespective inner die (126, 128) to move towards its extended position.Preferably, the actuator (142) is hydraulically actuated. Referring toFIG. 10, the actuator (142) is comprised of an inner punch assembly(144). In addition, the actuator (142) may also be comprised of an outerpunch assembly (146). The inner punch assembly (144) is associated withthe respective inner die (126, 128) for causing the inner die (126, 128)to move to the extended position. The outer punch assembly (146) isassociated with the respective press die (68, 70) for causing the pressdie (68, 70) to be extended to forge the tubular pipe (44).

More particularly, the inner punch assembly (144) includes a movable orreciprocable shaft, preferably an inner shaft (148) having a first end(150) and a second end (152). The first end (150) of the inner shaft(148) is associated with, and preferably connected, fastened orotherwise affixed with, the inner end (132) of the respective inner die(126, 128) such that reciprocation of the inner shaft (148) results inthe reciprocation of the inner die (126, 128). The second end (152) ofthe shaft (148) is associated with a hydraulic chamber (154), andpreferably is contained within the hydraulic chamber (154).

More preferably, the hydraulic chamber (154) is configured or adapted topermit a fluid communicated to the hydraulic chamber (154) to act uponthe second end (152). The second end (152) of the inner shaft (148) isalso preferably configured or adapted to facilitate or enhance theeffect or action of the fluid on the second end (152). For instance, thesecond end (152) may be shaped or configured as a disklike structure ora disk-shaped structure with a seal for movement within the compatiblehydraulic chamber (154) to provide a piston effect. Preferably, thefluid acts upon the second end (152) within the hydraulic chamber (154)to actuate the inner shaft (148) to reciprocate in a first direction tomove the inner die (126, 128) to its extended position. If desired, thefluid may further alternately act upon the second end (152) within thehydraulic chamber (154) to actuate the shaft (148) to reciprocate in anopposed second direction to move the inner die (126, 128) to itsretracted position.

As well, the hydraulic chamber (154) may be configured to limit themovement of the inner shaft (148) therein to provide a desired range oftravel of the inner shaft (148). Specifically, the second end (152) ofthe inner shaft (148) may be configured to abut an end of the hydraulicchamber (154) to limit the movement in the first direction. Similarly,the second end (152) of the inner shaft (148) may be configured to abutan opposed end of the hydraulic chamber (154) to limit the movement inthe second direction. If desired, one or more dampening or shockabsorbing mechanisms, such as a spring (156), may be associated with thehydraulic chamber (154) at either or each end thereof such that thesecond end (152) abuts the spring (156) as it moves to the end of thedesired range of travel within the hydraulic chamber (154) in either orboth directions.

The outer punch assembly (146) similarly includes a movable orreciprocable shaft, preferably a cylindrical outer shaft (158) having afirst end (160) and a second end (162). The first end (160) of the outershaft (158) is associated with, and preferably connected, fastened orotherwise affixed with, the respective press die (68, 70) such thatreciprocation of the outer shaft (158) results in the reciprocation ormovement of the press die (68, 70). The second end (162) of the outershaft (158) is associated with a hydraulic chamber (164), and preferablyis contained within the hydraulic chamber (164).

Although the inner and outer punch assemblies (144, 146) may be arrangedrelative to each other in any manner, preferably, as shown in FIG. 10,the inner shaft (148) of the inner punch assembly (144) extends orpasses through the outer punch assembly (146) for connection with theinner die (126, 128). More particularly, the inner shaft (148) of theinner punch assembly (144) extends or passes through both the outershaft (158) and the hydraulic chamber (164) of the outer punch assembly(146). Further, the outer shaft (158) and the hydraulic chamber (164) ofthe outer punch assembly (146) are configured to permit the inner shaft(148) of the inner punch assembly (144) to pass through them and topermit the inner die (126, 128) to pass therethrough to its respectiveextended position.

Further, the hydraulic chamber (164) of the outer punch assembly (146)is also configured or adapted to permit a fluid communicated to thehydraulic chamber (164) to act upon the second end (162) of the outershaft (158). The second end (162) of the outer shaft (158) is preferablyconfigured or adapted to facilitate or enhance the effect or action ofthe fluid on the second end (162). For instance, the second end (162)may also be shaped or configured as a disk-like structure or anannulus-shaped structure with a seal for movement within the compatiblehydraulic chamber (164) to provide a piston effect. Preferably, thefluid acts upon the second end (162) within the hydraulic chamber (164)to actuate the outer shaft (158) to reciprocate in a first direction toextend the respective press die (68, 70) within the holding cavity (66).If desired, the fluid may further alternately act upon the second end(162) within the hydraulic chamber (164) to actuate the outer shaft(158) to reciprocate in an opposed second direction to withdraw thepress die (68, 70) from the holding cavity (66).

The hydraulic chamber (164) may be configured to limit the movement ofthe outer shaft (158) therein to provide a desired range of travel ofthe outre shaft (158). Specifically, the second end (162) of the outershaft (158) may be configured to abut an end of the hydraulic chamber(164) to limit the movement in the first direction. Similarly, thesecond end (162) of the outer shaft (158) may be configured to abut anopposed end of the hydraulic chamber (164) to limit the movement in thesecond direction. If desired, one or more dampening or shock absorbingmechanisms, such as a spring (166), may be associated with the hydraulicchamber (164) at either or each end thereof such that the second end(162) abuts the spring (166) as it moves to the end of the desired rangeof travel within the hydraulic chamber (154) in either or bothdirections.

In operation, referring to FIG. 10, following the movement of theholding die assembly (58) to the closed position, the inner punchassembly (144) of each press die (68, 70) is hydraulically actuated tomove the inner shaft (148) in the first direction and thus move therespective inner die (126, 128) toward the extended position. Subsequentthereto or simultaneously therewith, the outer punch assembly (146) ishydraulically actuated to move the outer shaft (158) in the firstdirection and thus extend the respective press die (68, 70) within theholding cavity (66). The actuations of the inner punch assembly (144)and the outer punch assembly (146) are coordinated so that the innerdies (126, 128) reach their extended positions before the shifting ofthe material of the tubular pipe (44) progresses to the point at which“finning” could occur.

Following the forging of the tubular pipe (44) within the holding cavity(66), the inner punch assembly (144) is released. In other words,release of the hydraulic pressure within the hydraulic chamber (154)permits the inner shaft (148) to move in the second direction and thusmove the respective inner die (126, 128) to the retracted position.Alternately, the inner shaft (148) may be actively moved or actuated inthe second direction. Similarly, the outer punch assembly (146) isreleased. In other words, release of the hydraulic pressure within thehydraulic chamber (164) permits the outer shaft (158) to move in thesecond direction and thus withdraw the respective press die (68, 70)from the holding cavity (66). Alternately, the outer shaft (158) may beactively moved or actuated in the second direction. Also, the holdingassembly (58) is moved to the open position.

Thus, there are preferably three steps to be performed to release thepremium coupling blank (20) from the forging apparatus (56) afterforging, which steps may be performed in various orders, any of whichmay be appropriate in certain modes of operation. However, in thetypical or preferred mode of operation of the forging method describedherein, the preferred order of the method steps is, first, retraction ofthe inner dies (126, 128), second, withdrawal of the press dies (68, 70)and, third, movement of the holding die assembly (58) to the openposition.

Once the premium coupling blank (20) is produced by the forging methodand forging apparatus (56) as described herein, the premium couplingblank (20) is preferably subjected to further treating in order toachieve the desired or required material specifications of the premiumcoupling blank (20). Specifically, the premium coupling blank (20) ispreferably subjected to heat treating. Heat treating is required toprovide a premium coupling blank (20) suitable for later production of,and intended use as, a premium coupling (22) for a particularapplication, such as an OCTG premium coupling.

The heat treating is conducted according to known heat treatingtechniques and methods. Further, the particular heat treating techniqueor combination of techniques and the particular parameters of such heattreating techniques are selected such that the material properties ofthe premium coupling blank (20) may be altered thereby to provide a setof material properties which are suitable for use as the premiumcoupling (22). Thus, preferably, the heat treating techniques areselected to be suitable for use in heat treating metal components,particularly steel or stainless steel.

Preferably, heat treating of the forged product, preferably the premiumcoupling blank (20), is comprised of quenching and tempering,normalizing or annealing.

Austempering may be used as a substitute for conventional quenching andtempering. In this regard, austempering has been found to providedesirable cracking prevention properties, and may be more cost effectivethan conventional techniques in some applications.

However, where desired, any suitable heat treating technique ortechniques may be utilized that are capable of producing the desiredmaterial properties of the premium coupling blank (20). For instance,heat treating techniques may include normalizing or annealing. Inaddition, other heat treating techniques may include quenching and/ortempering. The following examples are provided of potential heattreating of the premium coupling blank (20).

For example, OCTG API Grades H40, J55, K55, N80 Type 1, M65 aretypically produced by no heat treating, normalizing or normalizing andtempering. However, some of these Grades may be produced by quenchingand tempering. Further, in order to produce premium coupling blanks (20)of these Grades, the premium coupling blank (20) is preferably forged atthe austenitizing temperature or the annealing temperature and slowlycooled. If the premium coupling blank (20) is forged at a temperaturelower than the annealing temperature, the premium coupling blank (20) ispreferably subjected to stress relief annealing or normalizing.

To provide material of OCTG API Grades N80 Type Q, L80 Type 1, L80 13Cr,L80 9Cr, C90 Type 1, C90 Type 2, C95, T95 Type 1, T95 Type 2, P110, Q125Type 1, Q125 Type 2, Q125 Type 3 and Q125 Type 4, the premium couplingblank (20) is typically quenched and tempered. Further, as specified forOCTG API Grades, the preferable minimum tempering temperature for GradeL80 type 1 is 1050° F. (about 565.55° C.), for Grade L80 9Cr and GradeL80 13Cr is 1100° F. (about 593.33° C.), for Grade C90 type 1 and 2 is1150° F. (about 621.11° C.), for Grade C95 is 1000° F. (about 537.78°C.) and for Grade T95 type 1 and 2 is 1200° F. (about 648.89° C.).

As well, in order to create premium coupling blanks (20) of theseGrades, the premium coupling blank (20) may be forged at anypredetermined temperature. If the premium coupling blank (20) is forgedat the austenitizing temperature, the blank (20) could be quenched ornormalized immediately following the forging. However, it is preferredthat after the premium coupling blank (20) is forged, the blank (20) isreheated to be processed for heat treating. During the process, it ispreferred that the residual heat from the forging be utilized.

Further, the austenitizing time is typically 1 hour per inch of wallthickness. In addition, a cooling rate is preferably provided of equalto or greater than about 100° F. (about 37.78° C.) per second (measuredat 1300° F. or about 704.44° C.) in order to obtain a maximum amount ofmartensite, which is usually the preferred as-quenched steelcomposition.

Finally, referring to FIG. 11, a model is provided for the massproduction of premium coupling blanks (20) using the present invention.Preferably, the production method is fully automated, such that one ormore robot arms may be used to load and unload the work pieces. Forinstance, first, the forging stock, preferably the steel or stainlesssteel tubular pipe (44) as described herein, is heated in a heater(168), such as a conveyor induction heater, to a suitable forgingtemperature. The forging stock is then conducted to the forgingapparatus (56) as described herein to produce the forged product,preferably the premium coupling blank (20).

The forged product may be subsequently subjected to an optional firstannealing process, such as by subjecting it to a first annealing roller(170) for a suitable period of time. Specifically, the forged productmay undergo the first roller annealing process for a period of 12 to 24hours.

Next, the forged product is subjected to quenching in a quenchintegrated furnace (172) and tempering in a temper furnace (174).However, for more efficient production, a conveyor style furnace mayalso be applied as a heat treating method. Finally, the forged productmay be subsequently subjected to an optional second annealing process,such as by subjecting it to a second annealing roller (176) for asuitable period of time. Specifically, the forged product may undergothe second roller annealing process for a period of 12 to 24 hours.

In this document, the word “comprising” is used in its non-limitingsense to mean that items following the word are included, but items notspecifically mentioned are not excluded. A reference to an element bythe indefinite article “a” does not exclude the possibility that morethan one of the elements is present, unless the context clearly requiresthat there be one and only one of the elements.

1. A forging apparatus comprising: (a) a holding die assembly having afirst end and a second end and defining a holding cavity extendingbetween the first end and the second end, the holding die assemblycomprising a first holding die defining a first portion of the holdingcavity and further comprising a second holding die opposed to the firstholding die and defining a second portion of the holding cavity, whereinthe first holding die and the second holding die are selectivelyrelatively movable toward each other to a closed position of the holdingdie assembly and away from each other to an open position of the holdingdie assembly, and wherein the first holding die, the second holding dieand the holding cavity are configured so that a forged product producedby the forging apparatus may be removed from the holding cavity when theholding die assembly is in the open position; and (b) a press dieapparatus comprising: (i) a first press die which is selectivelyreciprocable in order to extend within and withdraw from the holdingcavity from the first end of the holding die assembly; and (ii) a secondpress die which is selectively reciprocable in order to extend withinand withdraw from the holding cavity from the second end of the holdingdie assembly.
 2. The forging apparatus as claimed in claim 1 wherein theholding die assembly is further comprised of a first end retainer whichprojects into the holding cavity adjacent to the first end of theholding die assembly and wherein the holding die assembly is furthercomprised of a second end retainer which projects into the holdingcavity adjacent to the second end of the holding die assembly.
 3. Theforging apparatus as claimed in claim 2 wherein the first holding die iscomprised of a retainer member adjacent to the first end of the holdingdie assembly and wherein the first end retainer is comprised of theretainer member.
 4. The forging apparatus as claimed in claim 2 whereinthe second holding die is comprised of a retainer member adjacent to thefirst end of the holding die assembly and wherein the first end retaineris comprised of the retainer member.
 5. The forging apparatus as claimedin claim 2 wherein the first holding die is comprised of a retainermember adjacent to the second end of the holding die assembly andwherein the second end retainer is comprised of the retainer member. 6.The forging apparatus as claimed in claim 2 wherein the second holdingdie is comprised of a retainer member adjacent to the second end of theholding die assembly and wherein the second end retainer is comprised ofthe retainer member.
 7. The forging apparatus as claimed in claim 2wherein the first holding die is comprised of a retainer member adjacentto each of the first end and the second end of the holding die assembly,wherein the second holding die is comprised of a retainer memberadjacent to each of the first end and the second end of the holding dieassembly, and wherein the first end retainer and the second end retainerare comprised of the retainer members.
 8. The forging apparatus asclaimed in claim 1 wherein the first holding die and the second holdingdie define a holding die interface plane and wherein the holding dieinterface plane extends between the first end and the second end of theholding die assembly.
 9. The forging apparatus as claimed in claim 1wherein one of the first holding die and the second holding die is in afixed position and wherein the other of the first holding die and thesecond holding die is movable.
 10. The forging apparatus as claimed inclaim 9 wherein the first holding die and the second holding die definea holding die interface plane and wherein the first holding die and thesecond holding die are configured so that the holding die interfaceplane is substantially horizontal.
 11. The forging apparatus as claimedin claim 10 wherein the first holding die is a bottom holding die,wherein the second holding die is a top holding die, wherein the bottomholding die is fixed, and wherein the top holding die is movable. 12.The forging apparatus as claimed in claim 11 wherein the holding dieinterface plane extends between the first end and the second end of theholding die assembly.
 13. The forging apparatus as claimed in claim 1wherein the forging apparatus is configured to produce a premiumcoupling machining blank as the forged product.
 14. The forgingapparatus as claimed in claim 13 wherein the forging apparatus isconfigured to produce the premium coupling machining blank from a lengthof a tubular pipe as a forging stock, wherein the tubular pipe has awall thickness, wherein the premium coupling machining blank has amaximum wall thickness, and wherein the wall thickness of the tubularpipe is less than the maximum wall thickness of the premium couplingmachining blank.
 15. The forging apparatus as claimed in claim 14wherein the premium coupling machining blank has a minimum wallthickness and wherein the wall thickness of the tubular pipe is greaterthan the minimum wall thickness of the premium coupling machining blank.16. The forging apparatus as claimed in claim 14 wherein the premiumcoupling machining blank has a length and wherein the length of thepremium coupling machining blank is greater than the length of thetubular pipe.
 17. The forging apparatus as claimed in claim 14, furthercomprising a finning control mechanism for controlling finning betweenthe first press die and the second press die while the forged product isbeing produced by the forging apparatus.
 18. The forging apparatus asclaimed in claim 17 wherein the first press die and the second press diedefine a variable press die gap between them as they extend within andwithdraw from the holding cavity and wherein the finning controlmechanism is comprised of a variable spanning device for spanning thepress die gap throughout a range of the press die gap.
 19. The forgingapparatus as claimed in claim 18 wherein the spanning device iscomprised of an inner die telescopically received within a one of thefirst press die and the second press die such that the inner die iscapable of reciprocable movement, relative to the one of the first pressdie and the second press die, between an extended position and aretracted position in order to span the press die gap throughout therange of the press die gap.
 20. The forging apparatus as claimed inclaim 19 wherein the inner die is biased toward the extended positionand movable toward the retracted position by overcoming the bias. 21.The forging apparatus as claimed in claim 18 wherein the spanning deviceis comprised of a first inner die telescopically received within thefirst press die, wherein the first inner die is capable of reciprocablemovement relative to the first press die between an extended positionand a retracted position, wherein the spanning device is furthercomprised of a second inner die telescopically received within thesecond press die, and wherein the second inner die is capable ofreciprocable movement relative to the second press die between anextended position and a retracted position.
 22. The forging apparatus asclaimed in claim 21 wherein the first inner die and the second inner dieare adapted to engage each other as the first press die and the secondpress die are extended within the holding cavity in order to span thepress die gap throughout the range of the press die gap.
 23. The forgingapparatus as claimed in claim 22 wherein the first inner die and thesecond inner die are each biased toward the extended position andmovable toward the retracted position by overcoming the bias.
 24. Theforging apparatus as claimed in claim 23, further comprising a firstbiasing mechanism for biasing the first inner die toward the extendedposition and further comprising a second biasing mechanism for biasingthe second inner die toward the extended position.
 25. The forgingapparatus as claimed in claim 22 wherein the first inner die and thesecond inner die are each actuatable toward the extended position. 26.The forging apparatus as claimed in claim 25 wherein the first inner dieand the second inner die are each hydraulically actuatable toward theextended position.
 27. A forging apparatus comprising: (a) a holding dieassembly having a first end and a second end and defining a holdingcavity extending between the first end and the second end; (b) a pressdie apparatus comprising a first press die and a second press dieopposed to the first press die, wherein the first press die and thesecond press die are selectively relatively movable toward each otherwithin the holding cavity to a closed position of the press dieapparatus and away from each other to an open position of the press dieapparatus; and (c) a finning control mechanism for controlling finningbetween the first press die and the second press die while the forgedproduct is being produced by the forging apparatus.
 28. The forgingapparatus as claimed in claim 27 wherein the first press die and thesecond press die define a variable press die gap between them as theyrelatively move toward and away from each other and wherein the finningcontrol mechanism is comprised of a variable spanning device forspanning the press die gap throughout a range of the press die gap. 29.The forging apparatus as claimed in claim 28 wherein the spanning deviceis comprised of an inner die telescopically received within a one of thefirst press die and the second press die such that the inner die iscapable of reciprocable movement, relative to the one of the first pressdie and the second press die, between an extended position and aretracted position in order to span the press die gap throughout therange of the press die gap.
 30. The forging apparatus as claimed inclaim 29 wherein the inner die is biased toward the extended positionand movable toward the retracted position by overcoming the bias. 31.The forging apparatus as claimed in claim 28 wherein the spanning deviceis comprised of a first inner die telescopically received within thefirst press die, wherein the first inner die is capable of reciprocablemovement relative to the first press die between an extended positionand a retracted position, wherein the spanning device is furthercomprised of a second inner die telescopically received within thesecond press die, and wherein the second inner die is capable ofreciprocable movement relative to the second press die between anextended position and a retracted position.
 32. The forging apparatus asclaimed in claim 31 wherein the first inner die and the second inner dieare adapted to engage each other as the first press die and the secondpress die are extended within the holding cavity in order to span thepress die gap throughout the range of the press die gap.
 33. The forgingapparatus as claimed in claim 32 wherein the first inner die and thesecond inner die are each biased toward the extended position andmovable toward the retracted position by overcoming the bias.
 34. Theforging apparatus as claimed in claim 33, further comprising a firstbiasing mechanism for biasing the first inner die toward the extendedposition and further comprising a second biasing mechanism for biasingthe second inner die toward the extended position.
 35. The forgingapparatus as claimed in claim 32 wherein the first inner die and thesecond inner die are each actuatable toward the extended position. 36.The forging apparatus as claimed in claim 35 wherein the first inner dieand the second inner die are each hydraulically actuatable toward theextended position.
 37. A forging method for forging a forging stock intoa forged product, the forging method comprising: (a) providing a holdingdie assembly having a first end and a second end and defining a holdingcavity extending between the first end and the second end, the holdingdie assembly comprising a first holding die defining a first portion ofthe holding cavity and further comprising a second holding die opposedto the first holding die and defining a second portion of the holdingcavity, wherein the first holding die and the second holding die areselectively relatively movable toward each other to a closed position ofthe holding die assembly and away from each other to an open position ofthe holding die assembly; (b) positioning the forging stock between thefirst holding die and the second holding die when the holding dieassembly is in the open position; (c) relatively moving the firstholding die and the second holding die toward each other to the closedposition of the holding die assembly so that the forging stock ispositioned in the holding cavity between the first holding die and thesecond holding die; (d) providing a first press die which is selectivelyreciprocable in order to extend within and withdraw from the holdingcavity from the first end of the holding die assembly, and providing asecond press die which is selectively reciprocable in order to extendwithin and withdraw from the second end of the holding die assembly; (e)extending the first press die within the holding cavity from the firstend of the holding die assembly and extending the second press diewithin the holding cavity from the second end of the holding dieassembly in order to forge the forging stock, thereby producing theforged product; (f) withdrawing the first press die from the holdingcavity from the first end of the holding die assembly and withdrawingthe second press die from the holding cavity from the second end of theholding die assembly while maintaining the holding die assembly in theclosed position; (g) relatively moving the first holding die and thesecond holding die away from each other to the open position of theholding die assembly; and (h) removing the forged product from theholding cavity while the holding die assembly is in the open position.38. The forging method as claimed in claim 37, further comprisingretaining the forged product in the holding cavity while withdrawing thefirst press die from the holding cavity and withdrawing the second pressdie from the holding cavity.
 39. The forging method as claimed in claim38 wherein retaining the forged product in the holding cavity iscomprised of gripping the forged product between the first holding dieand the second holding die.
 40. The forging method as claimed in claim38 wherein retaining the forged product in the holding cavity iscomprised of engaging the forged product with a first end retainerassociated with the first end of the holding die assembly.
 41. Theforging method as claimed in claim 38 wherein retaining the forgedproduct in the holding cavity is comprised of engaging the forgedproduct with a second end retainer associated with the second end of theholding die assembly.
 42. The forging method as claimed in claim 40wherein retaining the forged product in the holding cavity is furthercomprised of engaging the forged product with a second end retainerassociated with the second end of the holding die assembly.
 43. Theforging method as claimed in claim 37 wherein the first holding die andthe second holding die define a holding die interface plane and whereinthe holding die interface plane extends between the first end and thesecond end of the holding die assembly.
 44. The forging method asclaimed in claim 37 wherein relatively moving the first holding die andthe second holding die is comprised of maintaining one of the firstholding die and the second holding die in a fixed position while movingthe other of the first holding die and the second holding die.
 45. Theforging method as claimed in claim 44 wherein the first holding die andthe second holding die define a holding die interface plane and whereinthe first holding die and the second holding die are configured so thatthe holding die interface plane is substantially horizontal.
 46. Theforging method as claimed in claim 45 wherein the first holding die is abottom holding die, wherein the second holding die is a top holding die,wherein the bottom holding die is maintained in the fixed position, andwherein the top holding die is movable.
 47. The forging method asclaimed in claim 46 wherein the holding die interface plane extendsbetween the first end and the second end of the holding die assembly.48. The forging method as claimed in claim 37 wherein the forged productis a premium coupling machining blank.
 49. The forging method as claimedin claim 48 wherein the forging stock is a length of a tubular pipe,wherein the tubular pipe has a wall thickness, wherein the premiumcoupling machining blank has a maximum wall thickness, and wherein thewall thickness of the tubular pipe is less than the maximum wallthickness of the premium coupling machining blank.
 50. The forgingmethod as claimed in claim 49 wherein the premium coupling machiningblank has a minimum wall thickness and wherein the wall thickness of thetubular pipe is greater than the minimum wall thickness of the premiumcoupling machining blank.
 51. The forging method as claimed in claim 49wherein the premium coupling machining blank has a length and whereinthe length of the premium coupling machining blank is greater than thelength of the tubular pipe.
 52. The forging method as claimed in claim49, further comprising controlling finning between the first press dieand the second press die while producing the forged product.
 53. Theforging method as claimed in claim 52 wherein the first press die andthe second press die define a variable press die gap between them asthey extend within and withdraw from the holding cavity and whereincontrolling finning is comprised of spanning the press die gapthroughout a range of the press die gap.
 54. The forging method asclaimed in claim 53 wherein spanning the press die gap is comprised ofproviding a variable spanning device for spanning the press die gapthroughout a range of the press die gap.
 55. The forging method asclaimed in claim 54 wherein the spanning device is comprised of an innerdie telescopically received within a one of the first press die and thesecond press die such that the inner die is capable of reciprocablemovement, relative to the one of the first press die and the secondpress die, between an extended position and a retracted position inorder to span the press die gap throughout the range of the press diegap.
 56. The forging method as claimed in claim 55 wherein spanning thepress die gap is further comprised of biasing the inner die toward theextended position and moving the inner die toward the retracted positionby overcoming the bias.
 57. The forging method as claimed in claim 54wherein the spanning device is comprised of a first inner dietelescopically received within the first press die, wherein the firstinner die is capable of reciprocable movement relative to the firstpress die between an extended position and a retracted position, whereinthe spanning device is further comprised of a second inner dietelescopically received within the second press die, and wherein thesecond inner die is capable of reciprocable movement relative to thesecond press die between an extended position and a retracted position.58. The forging method as claimed in claim 57 wherein spanning the pressdie gap is further comprised of engaging the first inner die and thesecond inner die with each other in order to span the press die gapthroughout the range of the press die gap.
 59. The forging method asclaimed in claim 58 wherein spanning the press die gap is furthercomprised of biasing each of the first inner die and the second innerdie toward the extended position and wherein spanning the press die gapis further comprised of moving the first inner die and the second innerdie toward the retracted position by overcoming the bias.
 60. Theforging method as claimed in claim 58 wherein spanning the press die gapis further comprised of actuating each of the first inner die and thesecond inner die toward the extended position.
 61. The forging method asclaimed in claim 60 wherein spanning the press die gap is furthercomprised of hydraulically actuating each of the first inner die and thesecond inner die toward the extended position.
 62. A forging method forforging a forging stock into a forged product, the forging methodcomprising: (a) providing a holding die assembly having a first end anda second end and defining a holding cavity extending between the firstend and the second end; (b) positioning the forging stock in the holdingcavity; (c) providing a press die apparatus comprising a first press dieand a second press die opposed to the first press die, wherein the firstpress die and the second press die are selectively relatively movabletoward each other within the holding cavity to a closed position of thepress die apparatus and away from each other to an open position of thepress die apparatus; (d) relatively moving the first press die and thesecond press die to the closed position of the press die apparatus inorder to forge the forging stock, thereby producing the forged product;(e) controlling finning between the first press die and the second pressdie while producing the forged product; (f) relatively moving the firstpress die and the second press die to the open position of the press dieapparatus; and (g) removing the forged product from the holding cavity.63. The forging method as claimed in claim 62 wherein the first pressdie and the second press die define a variable press die gap betweenthem as they relatively move toward and away from each other and whereincontrolling finning is comprised of spanning the press die gapthroughout a range of the press die gap.
 64. The forging method asclaimed in claim 63 wherein spanning the press die gap is comprised ofproviding a variable spanning device for spanning the press die gapthroughout a range of the press die gap.
 65. The forging method asclaimed in claim 64 wherein the spanning device is comprised of an innerdie telescopically received within a one of the first press die and thesecond press die such that the inner die is capable of reciprocablemovement, relative to the one of the first press die and the secondpress die, between an extended position and a retracted position inorder to span the press die gap throughout the range of the press diegap.
 66. The forging method as claimed in claim 65 wherein spanning thepress die gap is further comprised of biasing the inner die toward theextended position and moving the inner die toward the retracted positionby overcoming the bias.
 67. The forging method as claimed in claim 64wherein the spanning device is comprised of a first inner dietelescopically received within the first press die, wherein the firstinner die is capable of reciprocable movement relative to the firstpress die between an extended position and a retracted position, whereinthe spanning device is further comprised of a second inner dietelescopically received within the second press die, and wherein thesecond inner die is capable of reciprocable movement relative to thesecond press die between an extended position and a retracted position.68. The forging method as claimed in claim 67 wherein spanning the pressdie gap is further comprised of engaging the first inner die and thesecond inner die with each other in order to span the press die gapthroughout the range of the press die gap.
 69. The forging method asclaimed in claim 68 wherein spanning the press die gap is furthercomprised of biasing each of the first inner die and the second innerdie toward the extended position and wherein spanning the press die gapis further comprised of moving the first inner die and the second innerdie toward the retracted position by overcoming the bias.
 70. Theforging method as claimed in claim 68 wherein spanning the press die gapis further comprised of actuating each of the first inner die and thesecond inner die toward the extended position.
 71. The forging method asclaimed in claim 70 wherein spanning the press die gap is furthercomprised of hydraulically actuating each of the first inner die and thesecond inner die toward the extended position.